We routinely buy/sell crushed concrete around here. Makes a good road base material.
https://www.scctx.com/
Yep, but you aren't the peon packing it off for a peso. Having rock crushers and rebar recovery magnets and large trucks to haul it make it a much more viable commodity, plus, if the operation is set up right, they get paid to get it, and get paid for the crushed concrete and the salvaged scrap rebar, so they're making money on both ends of the operation.
Now little Jose and Pedro with a couple of sledgehammers and a pickup (maybe) aren't going to have that going for them.
OTOH, concertina wire can be 'harvested' with minimal tools....and pound for pound likely has a much better resale value.