You can say "too much" with a noun after it which gives the entire quantity as in "too much food", but when you have an adjective after it, this changes. You are describing "how long" which is "much too long". You could say "He is going much too fast." or "He has too much speed".
"Pants" is a tricky one, because they originally came in two pieces; one for each leg.
Of course they're now stitched together, forming a single garment, but it's still referred to as "pants" or "a pair of pants" in English.
In Norwegian you have the option of doing the same thing, using 'buksene' for a single pair of pants, but it's also common to use the "true" singular 'buksen' or 'buksa'.
Thank you! I did not pay attention to the way that seemed. I didn't associate this with all British speakers, but some British speakers have complained about this on Duolingo and that is where I learned about this. My mistake was to refer to "The British" (people) and I am changing the statement to just include the facts.