On Saturday, August 26, 2017 at 8:23:08 AM UTC-4, wrote:
I've heard dozens of stories of pilots outlanding their motor gliders
when the engine wouldn't start, to discover on the ground that they'd
forgotten to switch the fuel on.

At some point you have to ask - is this a pilot problem or a design problem?

It is a design problem. A start checklist that seems quite trivial on the
ground becomes unmanageable when you're low, dehydrated, hot, stressed,
exhausted, trying to stay in save position for safe landing when the motor
doesn't start...

I worked with manufacturer and ILEC on this some years back.
The fuel shut-off is required for certification, even though
far more accidents have been caused by fuel valve in wrong position
than fire incidents (fire is why shut-off is required).
Work-around is fuel shut-off that normally remains "on", as is
done in ArcusM for example. That's not possible on some older
designs (for example, fuel can siphon through carb when motor
is in retracted position - don't ask me how I know).

Ergonomic design is not so easy!
The newer systems are MUCH better, but still leave room for screw-up...