They are banned when spotted.
Assuming they're bots, and Mods are human, Mods can't win this

Correct. Only bots can combat spam at that pace. I'm trying to code a bot which automates my daily reporting tasks. The only problem is, there are no set of steps that I could establish which will be performed repeatedly by the bot. Considering I somehow manage to create a bot that does mass accounts reporting on basis of any set of criteria that I define, mods would still need an automation from there side to handle say daily 500 reports generated by the bot.