This is true, it does trigger with wet wood. Aside from framing lumber (2x4s, etc), most woodworking is done using kiln-dried hardwood, though.

I worked around a sawstop at the Stanford student shop for a couple of years, and saw it triggered a handful of times: once was a piece of mirrored acrylic, once was a (wet) oak stump, and once was a TA's finger (he was fine, just a nick).

We frequently turned the safety off if a student needed to cut something that we knew might trigger it - it's just a key that you turn next to the start/stop switch.

The blade is not always ruined - just depends on the blade you're using. We primarily used a blade with carbide tips (which is very common, though more expensive), and I never saw the blade ruined.

Personally, I would never buy a table saw without this technology. However, I'm not sure we need a law to require it.