I am an investor and on the board of a new racetrack being built down here in Austin, Texas (
www.drivewayaustin.com). I have also been on a couple of Skip Barber courses around the country, as have many others, I'm sure). At our track, EVERYONE has to sign such a waiver about responsibility etc., and if they are using our cars (we are JUST starting this part of the program), they will also have to sign a similar 'financial responsibility' clause as the one referred to above. I think it is fairly standard!
If the track does NOT have concrete barrier walls etc., but just grass runoffs, then I think you are pretty safe!
just my 2 cents worth, but LOVE to hear other experiences!
Glyn