>why can't it show the full problem so you could take a picture right as it happens and send it to your dealer for instant diagnosis?

Fault codes are uploaded to the manufacturer on modern cars with telematics. On mine, the app will say you have an engine fault (or need an oil change or recall) and offer to schedule an appropriate appointment. If you call them, they often have it already in their portal under your VIN. The manufacturer also keeps track of these for regulatory purposes (triggering recalls).

A single fault code doesn't mean much. That's like saying I got a segfault, please fix my problem. You need a stack trace, registers, what the user was doing at the time, whether they can reproduce it, etc.

OBD2 stores a _freeze frame_, most of its readings at the time of the fault. You also need to look at other fault codes, pending codes, frequency/history of the fault to make a diagnosis. In any case, you can't just give one code; it's 5 pages of readings.