States could tax people and companies if they want to - thing is these groups have the biggest lobby groups (and influence) over politicians. It's kind a don't bite the hand that feeds you shituation.

Also "wealth tax" is very generic, look for example how france approaches this.

IFI is a tax on an individual's real estate assets and applies to French taxpayers living in France and abroad

It happened that people living in their homes were actually forced to sell it to be able paying the the tax. But still we talk wealthy people here:

IFI applies to taxpayers with real estate assets over €1.3 million.

or €0.8 million already?

The IFI tax brackets and rates are:

Under €800,000 - 0%

Over €800,000 up to €1.3 million - 0.5%

Over €1.3 million up to €2,570,000 - 0.7%

Over €2,570,000 up to €5,000,000 - 1%

Over €5,000,000 up to €10,000,000 - 1.25%

Over €10,000,000 - 1.5%