I agree, it the amount seems to be random and have little to do with the actual incident. Although I'm pretty sure there is a human involved, sometimes it seems like the whole process is automatic.

It's been a few years since I've gotten $500. There seems to be some sort of magic $300 limit that they don't like to exceed unless it makes the news or something.
Last year, UA had misconnected me and caused and overnight delay because they were not willing to hold a plane 5min so that it would arrive 15min early. They only offered $300, I complained and to my surprise, they refused to budge. Usually they'll give a little more. I think the past year it has gotten slightly worse. On the return, I complained about something very minor, expecting maybe $100 at most and they threw me another $300. It's just random up to $300.

The proactive delay compensation is purely based on the local staff/crew putting in for the compensation. If they don't bother, then you have to request it manually. I typically find I'll get more this way though.

Now I think status and your class of service does make a difference. A few years back, I told them I have a million RDM in the bank and the last thing I need is more. They said they'd make a note to only offer ECT in the future and since then, they've never offered me miles so to my surprise, they actually listened.