Because at a certain point, fines punish lower level workers rather than management. Furthermore, if the company is large enough, fining it to the extent that it collapses has material effects on the economy, which governments are incentivized to avoid. This isn't to say that there shouldn't be financial consequences for breaking the law -- of course there should. But management should also be thrown in prison when the company breaks the law, because they're in a position of responsibility (it's what they get paid for). Either they knew -- in which case they're personally liable -- or they didn't, in which case they're criminally negligent, and again, personally liable.