Public relations for a startup like this would be hard to manage. I can already see the front page Reddit post with 4,000 upvotes on the game's subreddit asking why they lost $400 worth of items because one of the outsourced employees being paid $3/hour illegitimately banned them. Easy target to blame a company like this.

Cheater effort and quantity scales roughly with game revenue and popularity. So the first tier of games, the most popular and long-term ones, like League of Legends, CS:GO, Overwatch, maybe Valorant, Apex Legends, Fortnite, can afford machine learning. The next tier down can afford to implement community review programs, where players earn in-game rewards and the satisfaction of improving game experience.