This is much harder to evade - if you own most of Mayfair, you can't just move your assets elsewhere - they are very clearly tied to the location.
Of course, this would mean taxing powerful aristocrats, including the royal family. With their large majority, the British government had the opportunity to do this, but decided to take an easier path. The reason why this path was easier is now becoming clear to them.
I assume a new government dept. has to be set up to oversee it. Or do the wealthy self assess? Are things like shares and investments valued once? Once per year? How is a company valued? How do you know if you qualify as wealthy? Do we value everyone’s wealth? Can’t the wealthy just relocate or move assets out of reach?
I don’t expect answers to this, I’m just thinking out loud as there seem to be a lot of challenges.
A few countries seem to have tried and continued to tax wealth but it seems far from proven and only seems to “work” in Switzerland, which is a bit of an outlier
You don’t need new govt. dept. tax authority is enough. You do your yearly tax statement.
In NL they have access to your bank accounts or more like banks and brokers are obliged to provide state of accounts as per 1st of January.
Downside is you pay wealth tax on „possible gains” not actual gains on wealth above 40k€. If you have mortgage it of course is deducted from value of your house or any debts that you have documented.
In case you think collecting watches can make you hide the wealth, there are of course tax authority checks most likely if your wealth suddenly changes.