It would, if there was an actual will to "get some assholes" in the first place.
As reported by Private Eye several years ago, as soon as the current government got into power, several outstanding (and huge) tax-dodging cases were quietly settled, largely in favour of such dodgers. Once called on it, they reshuffled a couple of appointees and said it wouldn't happen again. I wouldn't be surprised to find the new bosses were told to put this list in the wrong drawer and accidentally forget about it entirely.
The previous government would have probably used the list for a fundraising round - if you can sell peerages, you might as well sell pardons. The next government will likely replace a few appointees here and there, and if pressed they will claim cases are too old to be efficiently investigated, it was all the previous guys' fault, etc etc.
So unless you lie at that point, you will not be prosecuted, only investigated.
This may let some tax dodgers off the hook, but it also ensures that genuine mistakes are not punished by jail time.
While this case is probably rather clear-cut, most cases are not. The Government doesn't actually want to put people in jail (what problem would that solve?), unlike the US Government - it just wants its money. The law seems reasonable to get that.
It first becomes tax evasion (in the UK anyway; details may vary) the moment you fail to report income or capital gains that are taxable, since the UK does not tax wealth.
Expect lengthy trials with all kinds of details showing up that creates sufficient doubt to make it hard to justify a prison sentence.
For starters, unless HMRC can prove that you have received the money in a way that should be taxed in the UK, they have no reason to expect you to report the money, and so most people don't.
E.g. for my part I'm Norwegian, but have been ordinarily resident in the UK for the last 13 years or so. The first year I lived here, I was not ordinarily resident for tax purposes, and maintained accounts in Norway that HMRC had no expectation of knowing anything about, and no legal basis for me to report.
But if I had had a large enough fortune and income, it'd have been trivial for me to maintain a status as not ordinarily resident much longer, and legally avoid reporting any income due from work done outside the UK at that point. The same is possible for UK citizens who move out of the UK to work for some time. For me there was no point, since all my income came from the UK, and so I brought my money into the UK once I'd tidied up my Norwegian affairs.
If you wish to defraud the HMRC, then, and create plausible deniability, you move out of the UK, or at least spend enough time outside the UK for a few years to be able to claim that when you receive that X million payment from WeAreTaxEvaders Ltd. in the Cayman Islands, directly to your secret account in Switzerland, it is income due to you entirely from work done outside the UK in a period where you were not resident in the UK for income tax purposes. Then you move back, and conveniently don't tell the HMRC because, you will claim, it has nothing at all to do with them (of course it is not at all because you don't want to risk that they take a closer look at the paper trails related to WeAreTaxEvaders Ltd. and maybe find traces of payments from the UK etc., or a timeline that doesn't match when you were abroad), and you way have had legitimate reasons to want to e.g. invest in Swiss shares or whatever at a later date when you retire to a cabin in the Swiss alps. Or whatever. If you are telling the truth about this, it is none of the HMRC's business that the money is sitting there unreported.
This is the problem with going after these schemes: There are any number of completely legal - for good reason, often, - mechanisms that allow the unscrupulous to create sufficient plausible deniability that actually proving a case becomes incredibly hard. It's easy to sit and assume that of course these are tax evaders. Except some non-trivial percentage of them are not.
HMRC risks not only not getting the actual tax evaders imprisoned, but not getting their hands on the money either, if they go to court on insufficient evidence. Going after just the money is a lot easier since people are often willing to pay to make the threat of further investigation go away even if they see the risk of prison as remote.
Now this is not true in all cases, of course. People who lead international lifestyles often find a Swiss account useful because everyone has heard of Swiss banks, and their association with international transfers long predates the SWIFT system. So it makes sense people King Abdullah of Jordan (who has zero tax liability as a monarch, but who is heavily engaged in diplomacy and power-brokerage), or the late Helmut Newton, a famous fashion photographer (who never had very much in his Swiss bank account - a few tens of thousands - but who worked all over the world).
So I don't think that having a Swiss bank account is dispositive of anything by itself, but at the same time it would be disingenuous to ignore the fact that they have often been used to obscure taxable income.
Why would that same rule not apply to other crime?
Furthermore, the same rule also applies to other crimes. The rule is called "innocent until proven guilty".
Murder someone, don't admit it, found out -> charged
Murder someone, admit it -> charged
Dodge tax, lie about it, found out -> charged
Dodge tax, don't lie about it, found out -> not charged!
HMRC say that [0]:
"Those who try to get an unfair advantage will have to pay:
- any tax that is due
- any interest that is due
- any penalties that are due"
Maybe it's a reasonable way for HMRC to do things but it's a bit weird that you can knowingly be in the wrong without having the risk of jail time hanging over you.
[0] http://webarchive.nationalarchives.gov.uk/+/http://www.hmrc....
Prosecuting the whole elite is not something that the elite typically does.
Or to send a warning? Would that really be effective?
What would be the cost? Was there anybody in the pot that was expendable, economically?
Yes. A lot of tax evaders who wouldn't even blink at a potential $500k fine would not take any risks if the were faced with real jail time. That means more tax revenue.
What do you mean by "economically expendable"?