Frank is right,most pax don't care.
9 out of 10 pax don't have a clue what they are or have flown on. My mother hates flying,she nearly died when i told her the UA
flight she booked from LHR
was a 777 and had 2 engines,i tell you,wish i'd not said anything!
Most people either book based on price or Airline/Alliance/Mileage accrual. There are the odd 'nuts' like me who will book to get on a new aircraft type.