Do you know whether or not those "kids" are operating in an official quiet zone or not? You can't just decide on your own to not blow the horn at 0300 - if it's not an officially designated quiet zone you MUST blow the horn at 0300. Do you have to lean on it for a minute or 2 (because you're only going 15mph)? No. But there are rules about how far in advance of the crossing you must blow the horn (20 seconds rings a bell for some reason).

There are sometimes exceptions even within quiet zones. On Sacramento RT, all of the grade crossings shared with real railroads are quiet zones - bell only absent an emergency - except at Jackson Hwy and Folsom Blvd where the horn is always required (and light rail trains operate through there every 15 min. to 1/2 hour each way from about 0430 to 0030). Jackson Highway is also SR 16, which might have something to do with it, and there have been a couple of significant grade crossing accidents there over the years (light rail started running there in 1985 or 86) which might also have something to do with it. Granted, light rail horns tend not to be as loud as regular train horns (more like a truck or bus) but they're loud enough and train horns often sound better (being tuned into chords).

Bottom line: they aren't blowing the horn to be obnoxious. It's a safety device.