If the problem is people leaving their car there for hours, is a $24/hr fine really that small? Yea, it might increase the number of people who leave their car there for 10 extra minutes, but it seems highly likely to address the real problem, which is low turnover at the Superchargers.
Even then, Tesla can very easily just increase the fine (or do something like a steadily increasing fine) to address this concern. They could also charge additional fees to anyone who leaves their car at a supercharger for too long serially (and my guess is that these are the real problem).
Maybe they should setup an overage amount - e.g. 1 hour / month that you're allowed to park for free. After that every hour that you charge results in warning letters etc. eventually you aren't allowed to charge at any of the stations. Probably a little extreme but might work.
Yea, if, as seems to be the crux of one criticism of the policy, is that it allows bad actors to simply pay for the privilege of their bad actions, penalties that scale to extreme quickly is probably the best method. It's unfortunate, since the (very large majority) of good actors are also at risk of punishment.
Even then, Tesla can very easily just increase the fine (or do something like a steadily increasing fine) to address this concern. They could also charge additional fees to anyone who leaves their car at a supercharger for too long serially (and my guess is that these are the real problem).