They make bot ban waves every now and then. It’s not like they’re completely oblivious to the problem.
It’s just that bot problems can’t be solved in a snap of fingers like people think. You are not just fighting bots, you are fighting smart people that program bots as well.
To make an automated system that prevents bots from playing the game they would need to dedicate a lot (and I really mean a lot) of efforts and man power to get it done. And even then, there’s a chance people with malicious intentions would find a way around the system and exploit it, making all that work building the system for nothing.
It’s easier for devs to try to control bots (but not fully prevent them) with simple-to-implement systems like the report system and dedicate those efforts into something else.