Man this thread is making me very thankful for my local site. In most instances hit calling is very good.
As others have said this comes down to marshalling. Like any sport if the referee isn't doing their job it turns to shit. It sounds like your site marshals just aren't doing the job, there might be a bunch of reasons why but it's moot at the end of the day.
I will say as it sounds like you're relatively new, check that your gun is actually accurate to the ranges you're shooting at. Many people eyeball the BBs going straight out to 30-40m and assume they keep going straight. Often, they hit a point where they just drop, or fly up to the moon, or do all sorts of squirrelly stuff. This is doubly so if you aren't holding your gun straight, as any tilt imparts left or right spin.
If you're making snapshots at close range, it's also much more likely than you'd think that you whiff the shots, especially if you're used to walking BBs onto a target and haven't got your sights zeroed.
Last note, the guys with £700 GBBs haven't got God weapons. They're expensive because of mechanical parts and other aspects of the design, but they're measurably worse than most AEGs unless they're very carefully tuned.
D Definitely check out a new site though. I'd have quit the hobby if my local was like this.