Bob,
what you said about the Dexter makes a lot of sense.
Commercial machines are supposed to have a high throughtput.
The more one can wash in the least time ... the more ca$h
So commercial frontloaders *without internal heater* (e.g. coin op ones) use that high level even in the main wash to have real hot water. The downside : half loads don't tumble properly but rather roll, so they don't get as clean as full loads.
Heated frontloaders (vintage and current, residential and commercial, cold fill only and hot/cold fill ones) use a lower level in the main wash to have proper tumbles with whatever load and rinse with levels up to 1/3 to have decent rinses.
That said, this was not always true. I have in the garage two vintage residential frontloaders. One has a 1/3 drum level and has the "full load only" issue. The other one has a 1/4 (maybe 1/5) level .... and doesn't wash well neither rinses well.
A 140°F cycle in both my mieles (one has around the same age the other 10 y.o) performs far better than a boilwash in the garage machines.
What doesn't make sense is that Frigidaire merged in Electrolux in 1986, two years later than Zanussi.
Zanussi machines had higher rinse levels, your Frigidaire doesn't. It seems that european and american headquarters didn't share their own know-how.
At least Whirlpool does. The Power Clean module first appeared on their american DW, now it's shared with euro models. On the opposite way frontloader know how from WP EU is used by WP NorthAmerica too.