Basically you can't sneak gotchas into a ToS, you have to make sure users know they're violating a rule. Ironically this is unlike actual laws where ignorance is not an excuse even if the law is weird and unexpected.
> Ironically this is unlike actual laws where ignorance is not an excuse
I think it's similar to real laws.
Unacceptable rules: sneaking in terms such as that your firstborn child will belong to me is not enforceable: nobody could expect or would agree to that. In law, similarly, you can't just upend someone's life for a minor infraction, or indeed take a child in exchange for your use of an ordinary government service. If this were to pass, a court would strike it down based on human rights or constitution, so you'd have to change/disavow those also as a country.
Acceptable rules: sneaking in terms that are fair are enforceable. Your third party client ban is an example where the rule is acceptable, but the consequences deemed disproportionate and so a warning is in order before cutting one off. This is similar to many laws, for example mildly dangerous driving gets you a fine or few days/weeks of driving ban. It takes repeat offences to get banned outright. Failure to pay taxes doesn't result in them showing up to auction your TV off, but they send a nice letter first, even if they'll eventually show up with a writ and after you're been warned that this is the next step, because indeed, we don't expect everyone to know everything.
I'm not a lawyer and can't cite relevant cases or anything, but this is my impression of law as a lay person. It's rarely perfectly fair towards everyone in all situations, and I think we should pay even more heed to "but how was I supposed to know"s whenever a situation is legitimately complex and good intent was shown (to avoid that people avoid doing good things because they don't know what legal risk it puts them in, such as what good samaritan laws are aimed to avoid), but it does try to find balances between what people can reasonably know and follow, at least in northwestern Europe which I'm most familiar with.
Yeah, that's the theory. But what a judge will decide qualifies for "minor" may or may not align with what is sane or what most people believe, and this gets worse and worse if you go into higher courts with politically appointed judges.
On practice governments upend people lives all the time, even for presumed infractions that may not be there at all.
Edit: from a place like Germany as the person above was talking about, to be clear. If such things are trivial to find in the USA would not surprise me in the slightest
There is a lot to be learned in this regard from financial products online. Most of them have built in functionality to let users know what they are doing and the associated risk.
Note that this also requires the user to be informed about what they will have to pay before they click the button. No bullshit surprise charges or hidden fees, mostly.
This is very interesting. Thanks for sharing.