Not in any country that believes in equality before the law; the concept is that you're not allowed to create 2 classes of citizens, which is what this law effectively does.
Not that the US is at all perfect in this regard, and nearly every state establishes some form of this, but effectively making a group of citizens permanent children should be troubling to anyone who values the concept of equality before the law.
Crucially, however, none of those rules involve criminal or civil penalties (outside of the distinction between who is and is not considered a full member of society; there are no tiers between full members outside of "does qualify as an adult" and "does not qualify").
It's worth noting that the part of the Constitution that deals with this was laid down after the US fought an incredibly destructive 4-year war against itself *to deny itself its own ability to pass cohort-based law*, though it took a good 100 years after that war for the results to be fully incorporated.
Of course, the US certainly isn't perfect in this regard, and this can be abused in the other direction ("In its majestic equality the law forbids both rich and poor to sleep beneath bridges...") but "honor what the 14th says" remains the cultural law of the land for very good reason.
>Maybe there are times when cohort based law is a good tool
Apartheid schemes and Jim Crow laws have always enjoyed wide popular support- they all have valid anecdotal backing (and scientific backing, if you consider P-hacking valid science), direct society in ways those not targeted by the law find preferable, and have enjoyed wildly popular support amongst the groups not targeted by the law.
That's fundamentally what cohort-based law is; society hasn't managed to solve the obvious abuse problems that come with "but I'm too lazy to solve this problem the right way" or "the solution to the problem compatible with human rights is taking too long", because without fail that's what it always becomes.
> Some people will never receive the access in the first place
This simply isn't true. People will purchase nicotine from older people, while that's still possible, and then there will be a blossoming bootleg nicotine market.
We've seen prohibition fail enough times to know that it simply doesn't work.
1. Market will shrink, making tobacco more difficult to obtain for current users and suppliers
2. Population will age, and it will become harder and harder for new generations to obtain access.
3. At some point, the policy might be considered excessive and abolished. However, there is no time frame for that. 5 years? 50 years? Will it have accomplished anything?
4. (same as your last point) As legalization of other drugs seems to gain traction, this seems like a weird position to take. Would illegal trafficking of tobacco increase, with the usual downsides?
Instead of a blanket ban, would a huge tax increase work better? Keeping the same age restrictions. I can imagine most people preferring a legal, though more expensive, procurement source. Of course, that discriminates against a growing part of the population, but so does a ban. And in both cases, it helps you not to take up the habit in the fist place.
I think the view that the government grants rights rather than takes away natural freedoms is a dangerous view.
Good parents don't parent via restrictions, but by offering kids something better to do with their time. Restrictions are powerful if they are super-clear and super-limited ("do not kill", "do not steal"). Just making a pile of good-to-have "don'ts" diminishes the effect and risks brewing revolt.
If you manage society and worry that people smoke too much or drink too much, or don't do enough sports, or eat junk food, figure out a way to make a better alternative more available and more satisfying. Be a good parent who guides to a better way, not an annoying parent who simply barks "no" left and right.
Not all freedoms are the same. Losing one doesn't equate with losing all of them. Equating the freedom to become addicted (or indebted perpetually) is not the same as the freedom to read or travel, etc.
Data. Decades of data and the societal costs of ignoring addictive substances. The rest of your comment is a set of false equivalencies.