It should be some more reasonable fine like $4000 on the spot fine and $9000 max penalty.
I'm not sure anyone would call those amounts 'more reasonable'... They're ridiculously high. I do agree, however, that people blocking doors and delaying trains is very frustrating, whether it's done intentionally or not.
I personally don't think there's anything wrong with the size of the current penalties, but as bowralcommuter
alluded to, there needs to be more policing of them (along with other offences such as fare evasion or smoking on platforms).
Raising fines to $4000 or $9000 (or even $50,000) will have no impact at all if there's no one there to police/issue them.