Many economists argue for taxing every equal sized plot of land the same (vs. taxing based on assessed value). There are a lot of benefits to doing it this way, but the main one is that it encourages efficient land use. If a 40 story high rise with 200 apartments in it is taxed the same way as a lot with 6 ranch style homes, then you're going to incentivize building up.
If you're thinking of land value taxes (Henry George style taxes, considered highly efficient), it's not taxing every property that's the same size the same exact amount. It's taxing each property based on its raw (unimproved) value. So an acre near a subway would be worth more than an acre that's further away, and would be taxed more, even if it was just an empty plot while the further away lot had a high rise on it.
