I use the e-gates almost every week across Europe, on the whole the e-gates system works well, I very rarely (maybe once this year) get referred to the manual gate, observations whilst waiting in the queue are that it is rare for people to get referred and most of those that do give the impression that they are “technophobes” . the best gates are in Germany where the passport is inserted before entering the machine and whilst the person before you is being checked by the machine, this speeds up the transaction time. The worst machines are the ones that grab your passport and pull it onto the machine; I fear passport damage and a visit to the embassy for a replacement every time.
it is rare in the extreme for me to compliment government but the e-gates work, now all they have to do is sort out the queue’s at Stansted border control and it will need another 100 e-gates to do that