Last I checked, they hadn't actually met those goals. They had attained 36tph for almost 2 hours in the mornings (about one round trip) and 1 hour in the afternoon as of the middle of last year. If they have surpassed that and are achieving 36tph for the full 3 hour peak period, then fantastic.
But that's still not a 90 second headway.
You people have never ridden a fully automated system, have you?
They make the Yonge Line feel clunky and slow. And the number of systems built and under construction with the ability to run at 90 seconds from day one are numerous.
As for automated systems, yeah, I've ridden hundreds, thanks. Extremely few of them operate at a 90 second headway over the whole of the line. It is very difficult to design a stub-ended terminal to allow for that kind of headway, even assuming GoA3 or 4.