Rents are "unearned" in the same way all appreciation is unearned. You spend your money on something, anybody else could also have spent that money on it, but the person who does spend the money on it enjoys the appreciation, if any, because they pay the opportunity cost.

> because land value always goes up

Tell that to the people who left urban St. Louis and Detroit and Cleveland in droves over the last 75 years. Their land didn't just go down in value; it went to less than zero. You'd literally have to pay somebody to take it and it's a huge burden on those municipalities.

The problem with Georgism is that, yes, land is different than other things in that you can't make more of it, but it's also the same as most things in most ways that matter.