Re: Who are you?
I haven't had one of those machine work yet at Gatwick or Heathrow. I travel a bit less than you but still 2-3 trips a year.
One of the immigration guys once told me it might be the combination of common first and last names I have and I know someone with the same name has been deported from the US as when I got pulled into a back room there once they actually gave me the courtesy of saying why after it was all cleared up that it wasn't me.
I had been thinking of trying a freedom of information request to see if I could find out more or possibly get it changed if it is unfairly profiling by name. It is still faster to go through it and use the failed attempt desks than the full non-EU passport control but it is a pain to have to do it every single time and especially as my travelling companions go through without issue and have to wait around for me.