Yes there's no denying , I've seen some pretty poor form myself by home grown "anglers" over the last few years.
Admittedly it could be anybody, without seeing who lifted the lines you won't know who the culprits are for sure. It's just that we are out just about every week all year round weather permitting,and I have never came across set lines, especially crude affairs like these, (they weren't even anchored well to hold them in the area) during many years, nor do I know anyone else who has. We showed this stuff to another angler who arrived and he knew of a similar set up which had been found nearby, and there have been a few foreign anglers fishing the general area recently, in fact I arrived to fish one early morning last year and there were some who'd been sleeping in a car over night . Again I suppose that proves nothing, but whoever it is, if you see any they want removed, because the way they had been set, birds were likely to get tangled in them and anglers are likely to be blamed when a passer by finds them.