"The 48 units represent their estimated percent of usage of the total capability."

It's a premium issue...I could see your point of usage if it was not for full premium flights.

IMO...as a premium,  all seats should have them irregardless.

IMO....they're afforded free to patronage with a request for pre arranged seating....from what I gather...eVu is equipped with a card swipe.

Two different markets....for that,  card swipe embedded in a seat back for paying customers would allow for a plane to be fully equipped.

doni