Most rich people keep very little in cash, relative to their wealth/income. It all goes to investments/shell corporations.
Now, if the government said they would police corporate bank accounts only, I'd be on board with that. This is going to mostly be used to target the waitress who didn't report $500 in tips over 10 years, which with interest and penalties, will work out to 10K.
They'll know about it in year 1, but they'll keep it on file till it gets big enough to be worth it to pursue, because there is no way the waitress who owes the IRS 10K will be able to afford a lawyer for $20K to avoid paying the $10K. She'll cut a deal with the IRS for monthly payments stretching out over 5 years which will have her pay $12K in total.
I feel like somewhere along the line, we really fucked up making income tax OK. It should always have only been land taxes. I'd be fine with a 20% land tax every year. It would keep prices in check and let the poor save more money which can only be good for society. For example, in Quebec, every home needs to have some sort of sales tax added to it (not transfer tax). That is something like 10%. This keeps prices there depressed relative to the rest of Canada.
To summarize:
- Housing should not be an investment
- Government is (edit: still) fat and gay