It’s not taking pictures it’s getting them posted past the Great Firewall. Of course if they catch you you disappear.
Don’t try to leave by train:
Or by road:
https://www.youtube.com/watch?v=L51TOvEFaMw
Those aren’t third line, part-timer reserve troops. They’re equipped with at least the QBZ-95 bullpup rifle China was issuing only to front line troops until the QBZ-95-1 revised variant began to be issued a few years ago. QBZ-95s are now being passed down to second-line troops, but the ‘reservist’ equivalents are still using AK pattern rifles...
Someone in China is concerned enough to roll out the regular troops for this.