I think you're somewhat understating the requirements for upper youth matches. "Youth Football" covers a wide range of ages, pitch sizes, match lengths and player counts - what you're saying may well be accurate for U12's, but not upper age groups. It's been a while since I've done lower-age group football, but my more recent memory of U17s and U18s is that they're pretty much as demanding as I would expect for your average OA match, which I would generally peg at around 8km. 2 of those plus 2 marginally less demanding matches probably puts you in the 25km to 30km bracket - aka 2/3rds of a marathon.Whilst I agree with the previous comments regarding being g observed after already doing games that day being madness, I'm not having that 4 games in a day cant be done or done effectively.
Youth football your going to be doing 3 or 4km a game max. Less running, shorter games etc. 12-15km over a whole day. Mentally you'd be a bit bored of it all but it's perfectly possible IF you are at the required fitness levels to take it on. Its not a big physical ask if you're a regular runner for example or just physically fit
So while not an impossible amount of running for a fit person to manage across a day, it is the kind of running that I would usually expect someone to have been given a few months to specifically train for, rather than being thrust on them as a "Oh, you're doing 2/3rds of a marathon this weekend BTW". And that's completely taking out the mental fatigue required to simultaneously keep your concentration up for nearly 5 1/2 hours of refereeing.