No law or regulation is ever 100% effective in real life. Income tax is not collected 100% effectively. Should we not do it? Criminals are not caught 100% of the time, should we not do it?

Of course this won't be 100% effective, maybe 80-90% effective. That's all they need and expect from this system.

Exactly.

HN is constantly obsessed with is it perfectly effective?

No law, none, is perfectly effective. Speed limits certainly aren’t self enforcing, but remove your neighborhood’s speed limits first if you truly believe laws must be demonstrated perfect.