I guess the problem is that most users that play with an engine don't play bullet/blitz.
I do meet a lot of engine players on 3 minute blitz but then I just do very fast bullet moves and all of a sudden I'm losing with a 90 second advantage that cannot be recovered if the user persists on playing with an engine.
Maybe, but there are also few rapid "speed" runs, like from Daniel Naroditsky, while he has also faced cheaters, it doesn't seem 1 out of 7.
And Daniel Naroditsky definitely would have good internal cheating detection even when the user does it sparingly, as he can basically understand most lower rated opponent moves, and if it seems too good for this rating, he can know this from just few moves.
If there were 1 out of 7 opponents using an engine, he would never have 145 wins against 0 losses.
And again for bullet and blitz there are also quite many examples with 100W to 0L.
If you'd look at all the speed run videos Daniel has done, it definitely doesn't seem 1 out of 7.
Daniel also posts all the times he's facing a cheater to youtube, same with Chessbrah and others as it makes for a good content, good views as people are always interested in seeing a GM playing against a cheater.
Not sure what the aim of cheating is, probably going from a rating of 1500 to 2000 and the status that it brings. In the end you still win 50% of the games, just against higher rated players.
Playing against a GM would reveal your cheating instantly, it seems. It's like robbing the police station :)
People like steamrolling. It's part of why higher rated players smurf (for theirs and/or their audience's enjoyment) and do 'speedruns' in chess and most online games with ranking.
I do meet a lot of engine players on 3 minute blitz but then I just do very fast bullet moves and all of a sudden I'm losing with a 90 second advantage that cannot be recovered if the user persists on playing with an engine.