Before we start to legislate each other and act like a government with taxes
let's consider this. What really works best is a voluntary system. Voluntary
and anonymous contributions with occasional (say quarterly) reminders from
the list owner to consider an anonymous and voluntary contribution works
best.

A newcomer would shy away from any list that acts like a PBS station
constantly soliciting money and old timers and those who recently recent
benefit  will be happy to contribute once they realize their savings over
time.

So consider voluntary and anonymous contributions before we speculate on
taxing vendors or each other.

William