For London that's mainly because of the way fares work and the reduced number of stations and hours even though there's slightly more track. The system is divided up into zones encircling central London and depending on between which zones you are traveling and whether you are traveling at a peak hour, the fare goes up.

It would be like if within the bottom half of Manhattan, and within each borough the fare was 2.75 but then if you crossed between them you'd get charged an extra two dollars. There are also daily and weekly caps that depend on zones and peak times. It's a pretty complicated fare system.

The weekly cap for the largest zone travel is like 90 dollars, way more than the 33 dollar cap the MTA has.

The buses in London also work differently and some are much cheaper than the London Underground (and MTA) and have daily caps of like 5 dollars while others are more expensive.

Buses in London are also subsidized, unlike the trains. Makes sense considering there are over 700 lines and like 20 thousand bus stops in London, double that of the MTA.

The Tokyo metro also has ticket price tiers that depend on distance traveled (they still use paper tickets where you get a source and destination station iirc). These actually cap out at like $2.50 USD. Again though, beyond the cost of operation being cheaper in Japan, there are reduced hours and fewer stations and daily ridership is actually higher than the NYC subway.

All this is to say, these self funded systems depend on pretty different conditions from the MTA. The MTA to self fund like this would have to do a combination of hour reductions and tiered distance and congestion pricing.

It would be very expensive just to to make the logistical changes to how swipes work for that, but imo is also just not socially worth it. I'd rather have a progressive percentage tax on all city residents and businesses (to hit the commuters out of city) and make the whole system free than do some chicanery of "well we'll target 50 percent self funded so raise fares x amount, spend this much to do cross-borough pricing, and reduce hours by y".

We should also transition the MTA to being fully state owned, not the current public benefit corporation model.