Same reason we don’t cut thieves’ hands
something more incentivizing than a mere fine wants to be levied upon corporations to get them to follow the law, rather than just saving up money to pay an expected fine.
Also speeding becomes reckless driving (with jail time) and parking in dumb places gets your car towed (and possibly damaged) so banking in money to avoid rules isn’t always exactly a winning strategy.
But, putting on my economist hat; I can assure you that exponentially increasing fines will at some point create enough deterrence against such actions. Or better yet, it will be socially optimal for those idiots to keep breaking rules.