I'm fortunate in that I don't have a long drive to ride (there will most likely be sometime in my future though that I do travel to ride someplace else).
That said....I have gotten to the parking area, only to discover things not to be conducive to riding. If I'm taking the groomed trail a ways to get to where we hop off trail, this trail system has a hillsides that can (and do) slide into the trail at times....I judge by what I see. Once I never even made it out of the parking lot. I stayed there all morning, along with the FS Snow Rangers, warning peeps of the conditions (a lot of slides across the trail were reported to me by a reliable peep). I told folks it was totally their choice, but they were looking at some high danger out there. We got about half to turn around (and some had traveled here to ride, so were on vacation time). I also had avy brochures to hand out. I send them out to anyone for free to anyone whom PM's me with their name & address to send to, carry them in backpack to hand out, put them up in a few places.
There have been a few other times that we have left, only to discover many slides, and thus turned around and went back home. While we don't have the long drive.......loading sleds/gear/everything associated with it, then to turn around to do the reverse. PITA.......yeah, but worth our lives. We chose to just go home and be around to ride another day.
Most places we ride, the trail/path has a mountainside next to it is various spots......so to just get to the safer areas at times, that part of the ride isn't always safe.