It would be a logistical nightmare, consider the following from the article:
Warren’s IRS would demand an annual accounting of people’s wealth. Even if the intrusion of the question does not bother you, the complexity of the answer will. The price you paid for your house is known, but what is it worth 10 or 20 years later? Professionals could estimate and appraise it, but no one knows for sure until an arm’s-length sale is completed.
Local property taxes are based on assessments that rarely change from year to year — your township is more likely to adjust the tax rate than the nominal value because this takes far less effort from it. But the township is concerned with raising revenue, not redistributing wealth, as Warren is. Would that level of inexactitude be enough for the wealth taxers? Unlikely.
Every bit of property people own would be subject to these calculations. Stocks are easy enough, but only if they’re publicly traded. How much is a privately held corporation worth? Appraisers can estimate, but one working for the owner will estimate one direction while the government will estimate in another. Which is right? Audits would be frequent for anyone close to the cutoff.
We do this sort of accounting for estate tax purposes when someone dies, and proponents of the wealth tax will say we can do the same for that. But those transfers are as onerous as they are infrequent. The process of settling an estate often takes more than a year. Doing it every year would mean a perpetual audit. The costs of compliance would be massive, even when people are playing it straight. If they aren’t, or if the government thinks they aren’t, costs multiply even more rapidly.
These calculations would apply to everything a person owns: land, cars, buildings, furniture, livestock, heirlooms, keepsakes, collectables, and every other bit of personal property you can imagine. That not only means a tremendous effort and expense in calculating wealth each year, but it also means the government would know exactly what everyone in America owns at all times. Everything.
Emphasis mine. I’m pretty sure that the wealthy are going to have and army of lawyers and accounts to deal with such an intrusion, don’t you. The point is that one’s “wealth” is a very subjective figure and will in itself take tremendous time, costs and legal battles to figure out.