It's no surprise, of course. Free soloing is pretty much the most riveting thing you could watch on a screen, whereas every other form of climbing is frankly quite boring to watch if you don't know the sport intimately. Mostly, it's people pushing their own personal limits, without any risk whatsoever, on things they've aren't visually all that spectacular.
Here's an example of what most of us do:
I defy a non-climber to make it through 3 minutes of watching me fall off the same 15 foot tall rock. Climbers, however, will notice that there are harder moves on that stone than anything you'll find in Alex's big free solo videos. They'll also know, of course, that Alex would likely be able to send this thing on his first try, because this is well within his limit.
Those two facts, reconciled together with him having practiced the easy route in the solo video every bit as much as I did this little boulder problem, give you an idea of how unlikely it is that he would fall off it.
Sadly, that's all lost on non-climbers, who just see a spectacular thing happening way up in the sky, stripped of all context.
It's a cool sport, by the way, go give it a try some time and I bet you'll get hooked.