And, potentially, pull you over for complying with the speed limit if the normal rate around you is large. Either way, you could lose.
A poorly enforced law provides a tool for executives (the law enforcers) to legislate (make their own laws) without any say from the real legislators. It's a loophole of sorts in the US's separation of powers.
Take marijuana. It's illegal to smoke marijuana. It's not illegal to be black. Yet the selective enforcement of the marijuana law allows authorities in any given district to shape policy on race without ever having to explicitly put a law on the books.
This is why the Computer Fraud and Abuse Act is so dangerous. It is broad enough to be used as a tool to enforce laws that would be too unpopular to explicitly pass.
It's also why threats from the US government to "ban encryption" should not be taken idly. You think to yourself, "Certainly they couldn't ban encryption, nothing would work without it." But they wouldn't enforce it across the board, only selectively.
I remember reading a story of a multi-billion dollar corporation in Russia being sold for pennies on the dollar, essentially at gunpoint. Otherwise, they'd prosecute it for being run illegally, since essentially all corporations are run illegally, because that's how Russia's legal system is set up.
Last I checked, encryption _is_ banned in the U.S., isn't it? So it's already the case that the government could selectively jail people for using encryption, as it sees fit.
According to https://en.wikipedia.org/wiki/Bernstein_v._United_States, the regulations are still in effect. It doesn't say what the U.S. loosened them to, but they do still exist.
The officers argument to my dad was "why would you go so much slower than traffic (this is on i78 in PA, mean traffic is around 75 and he was going the posted 55) if you aren't trying to hide something by going the speed limit" when the back of his covered pickup was full.
Turns out he was just bringing china plates to my grandparents.
He didn't get ticketed for it, but it gave the police a legal reason to pull him over beyond arbitrary suspicions.