To be fair, most bot detection can't and isn't trying to catch 100% of bots. Generally the idea is to prevent repeated abuse, rather than stop every single instance of it.
In the case of the scalper bot you've linked, the goal of bot protection would be to make the bot's transactions so computationally expensive/slow that they miss out on most of their intended purchases.
In the case of the scalper bot you've linked, the goal of bot protection would be to make the bot's transactions so computationally expensive/slow that they miss out on most of their intended purchases.