They were made of plastic. They steal them to sell them to those who manufacture plastic parts and utensils... I don't know, it's just a hypothesis. They could also steal them to use them as water tanks or whatever, i.e. to store something.
The fact is that there are none left.
I like long exposure photography very much... And also macro photography. I don't have the equipment for the latter, but I can spare more time for the first.
Good hypothesis
yes time is needed for long exposures.
I have never tried macro, I have read you can actually do it with a standard lens if it allows close up focus