The barriers my local series uses are like 1x6's stacked up and are pretty solid so the penalty is denting/ flatting a rim or crashing. I'm not sure what the race promoters do mid race when someone bashes through a barrier but I would think they prolly aren't too happy about it, nor the rest of the field. In our series rules they ask you not to jump the barriers unless you can actually jump the barriers but there are no rules against doing it.
The "barriers" at my first race Saturday were two large tree trunks so people were walking all over them. I have also seen people stepping on the more common scaffold plank barriers so they are pretty sturdy and it's legal.
I think the flimsy ones you have seen are practice barriers used for training that are meant to be light and cheap.
They're usually pretty rock solid. Judging from my previous crashes and mishaps into barriers, it's going to take a lot to snap one of those suckers. Also, if you're hopping them its perfectly safe to hit the tops of them.
Like others have said, it's expected that the barriers will take some abuse.
If the ones in your local races are flimsy, maybe you could help improve the promoter's "learning curve" by hammering thru/over them. If the barriers fall down, it's not the racers fault (just like the cones)...
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