Half of my clocks don’t have this option, they are AM/PM, except for the analog clocks on the wall, which only show a 12 hour face. And no, they don’t have an additional set of hour markers. The ones I have that do have a 24 hour option, like the microwave oven in my kitchen, I set to show AM or PM. I don’t have much use for it in my everyday life, but if I do, it’s trivial to just make the adjustment in my head. I can’t get behind the OP’s rant, 24 hour time does make sense and avoids unnecessary confusion.
I work in GPS research and keep tabs on the world-wide network of GPS ground stations. Not only is everything in 24 format but I am constantly converting times from one local time to another. Nothing like having to remember if New Zealand is currently on Daylight Saving Time and the time offset to UTC so I can cover that to the local time in Montevideo.
Either system causes annoyance for people used to the other system, so that’s not a valid reason to use one over the other. But only one system allows for possible AM/PM ambiguities if the speaker isn’t clear.
I was recently made sport of by an acquaintance when he noticed my watch was on military time.
This is what we use at work, I think it’s a better system, and I have, in fact, been to an 0300 meeting.
mmm
I work for the military and it’s become habit.
Yeah, if you’re using it with people who’ve never had to figure out when 1330 is, 24-hr time is not a good idea.
What IS a good idea is communicating clearly. How hard is it to say “Forms are due by 1700 (5 pm)”?
I had a coworker tell us the story of the one young new hire who’d remind everyone of meetings using 24-hr time to sound quasi-military, and a couple of people would show up two hours late: “I was sure the email said 3:30! 1330, wha…?”
“Well, either say something to Mister Wanna-Be Corporal, or get used to subtracting 1200…”
It doesn’t take long to adjust to military time.
Buy a clock that displays it. Or set your phone’s clock to 24 hour.
At first you’ll find yourself subtracting 12.
Within three days you’ll think in 24 hour time.
I learned it working in IT.
Is it really all that hard to subtract 12?
We have to use it… all the train schedules around here are in it. That said, the 12-hour clock is very often used here too. And don’t get me started on the local confusion with date formats…
24 hour time is seeing more and more use in medicine, too. Not a problem for me.
You can buy a clock with a 24-hour dial to hang on your wall, but it is not the most usual item one runs into.
If you are writing code that involves time, 24 hour time is much, much easier to deal with.
I also write dates before months on checks. The UN did it that way, and my father did it because he worked there, so I do it also.
All my clocks, watches, computing thingies, etc, run on 24-hour time. Even my cars.
My employer runs on 24 time. With a mix of all 39 local timezones and UTC for extra spice. 
Plus DST of course. All conversations with fellow employees, whether at work or over a beer use 24 hour time.
When I was in IT our customers were government agencies of the emergency/first responder flavor. Who all used 24 hour time. So our firm did too.
My wife is also a USAF veteran and we exclusively use 24 hour time when speaking to one another. Just like everyone does in any country smart enough not to still use feet and inches. IOW, the entire planet except for the USA and that other perennial economic and scientific powerhouse Liberia.
IMO the OP is 100% doing it wrong.
Admittedly he’s got a lot of company, so I too generally convert logical convenient 24-hour time into illogical inconvenient am/pm time when talking to generic people. But I totally think of that as dumbing down, just like when I have to talk to a store clerk who barely speaks English and I switch to using only short words in short sentences spoken carefully.
It doesn’t matter. I still don’t know whether 00:00 today’s date was last night, or tonight. The same as I don’t know whether 12:00 pm is noon or midnight.
It’s 2017, folks. How come out modern technological civilization can’t figure out a way to express what time it is?
Seriously? Time counts up, not down. So zero occurs at the beginning of a day. 23:59:59.999999 occurs at the end of a day.
So 2017-10-29T00:00:00 is the first instant of Sunday = tomorrow as I write this.
To be sure there are ignorant or dumb people who get that wrong. Just like any other mistake involving humans. But there is no ambiguity.
FYI, if my notation above isn’t familiar it ought to be. ISO8601 is the only universally approved date/time format. See ISO 8601 - Wikipedia and on a lighter note xkcd: ISO 8601 and xkcd: Standards
Uh, any clock can have a 24 hr face. It just requires that the numbers be written twice. You know, under the 1 is a 13, under the 2 is a 14, &c. The clock in my barracks looked like that, and so did almost every clock I saw in Moscow in 1977.
I meant a clock face in which the hour hand completes one rotation every 24 hours instead of every 12. They exist, but in my experience, and I see also in yours, are not commonly encountered.
ETA except maybe as sundials, but that is not quite the same.
There’s certainly no confusing 12 noon with 12 midnight.
There are strange things done in the midnight sun
By the men who moil for gold;
The Arctic trails have their secret tales
That would make your blood run cold
We have. The problem isn’t with the rest of the world.