Property tax is double taxation. Taxed once on the purchase, and taxed in perpetuity just for owning it.
The right to private property ownership is also pretty fundamental to this country (I don't expect liberals to really "get" that or respect it, but it is). Taxing someone in perpetuity just to keep something they already purchased is absurdly unfair.
And if your position is that we should have property tax, but we shouldn't really enforce it on little old ladies who get behind on their tax bills, you're just proving the problem with property tax.
Sales tax is the least worst across-the-board tax. We should pay for more things based upon usage, like toll roads and private schools.