Well if I bought a British tractor I would put gauges on it too. They didn't call Lucas (electrical system supplier) 'Prince of Darkness' for nothing.

BTDT with a few British motorcycles back in the pre-Honda era. One (BSA 350) I had to have a transmission bearing made for me one-off, its internals were underdesigned for a far earlier 250 and had no business in a 350.
Basically keeping a British vehicle running before they had competition from Japan, was 'fix it on Saturday before taking it out for a drive on Sunday'. I'll bet from time to time you actually saw something significant on those gauges. I agree they were needed.
Yanmar on the other hand designs stuff so it doesn't need that constant wariness. It just runs, for decades, so long as it has reasonable maintenance and occasional verification that everything is up to spec.
I checked my oil pressure once!
35 psi at 1500 rpm. Just fine for an engine with over a thousand hours and I suspect over 2,000.
And I had my first YM186D dyno-tested when I bought it, only because I had the seller drop it off at the pro shop of a friend. As thrashed as that tractor looked, it tested exceeding the new-tractor hp spec published 30 years prior. Nothing to worry about there.
My point is I think Yanmar got a lot of things right, we don't need to monitor every little thing as a component of operating them. They just run. Warning lights are sufficient to note if anything should ever get out of spec.