OT lawyers: waiving negligence via a "hold harmless" document

Here's the situation- I prepaid several hundred dollars to participate in an event for my kids and I while on vacation. When I arrived, I was forced to sign a "hold harmless" document just as we were all about to participate in the activity.

I understand that you waive certain rights when participating in high-risk activities such as skydiving or anything to do with wild animals, etc. But the language on many of these agreements are total bullshite.

This one on particular read, "It is my intention by signing this that I will not sue or hold 'xxxxx facility' or its employees liable or responsible for any injury or death or damages, regardless of fault, negligence or gross negligence of this facility or its employees."

In other words, the owner could have an employee that they knew was a crack addict drive a piece of heavy machinery right into a family and there's nothing anyone could do about it from a civil suit perspective?

I know the answer is to simply walk out but I had paid a good deal of money and flown halfway across to country to visit places like this and the waiver was never mentioned on the website. I've seen these waivers more and more often, too, at everything from local fairs to batting cages to sports complexes. The place I visited wasn't particularly dangerous and of course nothing happened, but my question is do these blanket "hold harmless" agreements hold any real legal water?