First the banks have to foreclose. From what I can tell anecdotally, there are a lot of unforeclosed-upon properties still out there. I don’t understand the banking business well enough to know why. Part of it might be the system is overwhelmed, part of it the issue of poor documentation slowing the process, part of it that when they foreclose, the banks have to take the write-off. Or at least that is my guess.
The banks don’t have to pay property taxes, until the properties are sold again. There aren’t many buyers. The bankers’ local friends in government want revenues. Some who are being foreclosed upon might be willing to continue paying property taxes.