Also who would you even send it to? How do you guarantee they receive it? If you do certified mail that is a cost and another thing to take up your time.
None of this is a problem for me, but I fully understand why dishonest businessfolk love to exploit the hell out of these "tiny conditions" and then turn around and pretend they don't understand why they are a big deal.
Yes, the correct solution is certainly to pass laws that force companies to enable easy and quick unsubscribe process.
Just commenting on that between the two bad choices of hours and hours on hold, or 10 minutes in the post office, I'll take the latter.