While the current standard will have most likely shifted as explained in other answers I will explain why that
is absolutely can be the wrong direction to go.
TlDr.: All together the system is very much imbalanced in favor of the government: BIG (essentially unlimited funds), good at getting people convicted, very little skin in the game vs. accused: small, limited funds, not good at the whole law/court game, huge losses possible.
There a number of reasons for presumption of innocence, one was given by hszmv above: It is hard to prove you didn't do something.
There is/was a discussion below hszmv's answer, explaining how that doesn't apply to money since you always have income statements, receipts etc. It is true that in general the amount of laws currently in place regarding money tracing is substantial (that is a big problem in itself), but it is still quite easy for a company - especially one that is not particularly big - to have problems proving the origin of all the money it owns (has in the bank account). That is even assuming they made no mistakes when actually accounting for it and taxed every penny, which is something that can go wrong by itself without malice (thus without the appropriate response from the state being confiscation).
It is quite possible to lose receipts and statements over time. Not everyone has a perfect filing system that survives 10 years with no hitches (the usual statute of limitations). Companies move, things get misplaced etc.
But it being hard to prove the negative is just one argument for presumption of innocence. The bigger one in my mind is: It's costly and hard to prove you didn't do anything wrong.
The reason the government has to prove you did something wrong and usually beyond a reasonable doubt, is that the government is BIG, and if they accuse a citizen of something, the amount of muscle they can put behind proving them guilty is very large. There are police forces trying to prove a person is guilty of something, and not only are they generally (well) funded, but they have lots of time to try and prove whatever they think is true. It's their job, they get paid for it, and can spend months on a case. They are also quite good at it. They know the system well, (they are the system to some degree) it is not their first rodeo, so to speak. They've tried many people before and will try many after. If it doesn't work out, they generally feel little repercussion, if any. "Oh well didn't get him, life goes on. Just turn up to work again tomorrow."
On the other hand the accused is - with some exceptions (multinationals) - much smaller than the government. They have to make money as they fight whatever case the government brought, or while they sift through the last 6 years of accounts to prove where that money came from. Usually they have to hire someone to help them since they don't know what standard of proof is necessary, who to give the proof to, how to present it etc. And if the accused loses there are severe repercussions, from asset seizure, loss of good name (that can occur even if you win persuasively), extra scrutiny, all the way to serious jail time.