Easy way to find bot users
Simple way for supercell to find and ban people who use bots to raid.
Add a button in the defense log to "Report a bot". If a real player views a defense replay and it's obviously a bot, they can press it to report it to supercell. To stop people going overboard, you can have a 24 hour cooldown on the button.
Now you might think supercell doesn't have the manpower to view a million replays every day, but they don't need to.
By nature, a bot user will be attacking many people in a day. Supercell only needs look at the players who are reported multiple times by separate individuals in 24 hour span. Supercell can take a look at those replays, make a judgement and ban if necessary.
Other metrics can help to determine if a player is truly a bot user such as time spent online in a day.
If they did this, then using bots would become unprofitable very quickly.
Btw: It is in supercell's interest to stamp out bot usage. Not only does it have a large negative effect on the people who play and enjoy this game, it directly impacts supercell's profit. If people can simply bot their resources, they will spend less on gems.