End gangways also create the flexibility to re-form three two-car units as two three-car units. These probably spend most of their time not coupled to anything else so the lack of end gangways is less important than with the 2-car 150/1s that are often seen in pairs these days.
While it depends which way you see it, that's just sloppy ordering by the TOCs.
Nobody has ordered any DMUs since
Midland Mainline with the 222s London Midlands' 172s, but before that, there was a long stretch of none, yet increased demand all over the place.
But then this where I don't understand.
The Government can say X coaches aren't compliant by X date and thus can't run. But in fact, we'll create some sort of paperwork that says they can.
So in this time when we're short of DMUs, there
could be some paperwork that says non emission-compliant trains could be built to ease the problem.