One obvious difference is that property taxes are applied uniformly and predictably --- a whole industry exists to plan around them --- and eminent domain is not, so widespread application of ED would create uncertainty that would discourage positive activity.
What’s “predictable” about having to pay taxes on a property that you don’t know how much will appreciate? Someone who bought a house 30 years ago while they were working, paid it off and had enough in savings to pay their bills but not pay taxes on a house that went up 10x the rate of inflation couldn’t predict their tax bill.
What happens when they can’t pay their taxes? The government takes it.
This is an unserious argument. ED and property taxes aren't comparably unpredictable. An obvious illustration of this would be the fact that most places in the US don't have California's cap, and people manage tax planning just fine. If your real argument is, essentially, "taxation is theft", that's a coherent position, but since most people don't agree with the premise, you're not left with much to contribute to this particular discussion.
In addition to what tptacek said, taxes are paid with money which is an infinitely fungible commodity. Eminent domain confiscates a specific piece of property that cannot be precisely replaced.