Well, I can't speak for anyone else... but when I read the 'Detecting And Disabling A Trap' section on page 120 of the DMG... it talk about how traps will specify the checks and DCs needed to detect it, disable it, or both... how characters who decide to actively look for a trap can make a check and how people just passing by can make passive checks... how if a character detects it you can call for an Investigation check to determine how it works and deduce what needs to be done to sabotage it... and that most trap's descriptions are clear enough to adjudicate whether a character's actions locate or foil the traps. The very basic questions you ask are all there in a basic form (at least to me). The only thing it doesn't state specifically is the exact time it would take... and sure, I'd have no problem if the game said a standard search of a room or the disabling of a trap took "10 minutes" (or whatever). Put it on the same timetable as casting a ritual, that's fine. But in truth, I don't even think noodling that much about granular time like that is really that worthwhile to most players anyway. How long does it take to disarm a trap? As long as it needs to take. The actual amount of time doesn't actually matter because everything moves at their own pace and not on any strict timetable. And if a trap disarm needs to go faster or slower from "however long it needs to take"... the specific amount of time it takes and the reason why it takes that long would be built into the description of the trap itself.
Worrying about time in most non-combat D&D situations to me seems rather pointless and I don't feel as though the game needs to add it in. I personally don't think the game gains anything for doing that. It's the same reason why I think the One D&D playtest packets having new "Actions" like Influence [Action], Search [Action] and Study [Action] are unnecessary, because no one does any of this stuff in a counting situation where having it take an "action" (aka 6 seconds) actually matters. If you are walking down a corridor and not in initiative, it does not matter in the slightest how long influencing, searching, or studying take... so calling them Actions is adding a descriptive point that doesn't need to be there. And I would say Disarming a Trap falls into the same thing. 6 seconds, 1 minute, 10 minutes... unless it matters for the trap itself (and thus would be written into its description), I don't feel there is any use to be gained by choosing one time period arbitrarily and putting it in the book. Now ultimately I wouldn't care if WotC did do that... but I don't personally feel anything is lost if they don't.