[londons_explore]

If you're happy for your gliders to travel at 100 mph instead of 500 mph, you can glide almost fuel free, making use of thermals and winds most of the way.

However, the finances for such a business are hard to make work since, while you save on fuel, your very expensive aircraft does fewer flights per year.

The only way to make it work would be very cheap airframes, probably without humans aboard (meaning factors of safety and maintenance costs can be dropped).

But developing new airframes is awfully hard.

[nradov]

Only sport gliders carrying a maximum of 2 people achieve those speeds fuel free. A large, heavy cargo glider carrying a full load is just going to crash without a tow rope, regardless of winds or thermals.

[londons_explore]

You probably wouldn't go totally fuel free - you'd go mostly fuel free.

And yes, the craft would have to be absolutely huge for a decent payload - and it might make sense to use different construction techniques considering that - for example an inflatable fully pressurised craft.

[BizarroLand]

Could probably add relatively inexpensive drone systems to the gliders with some solar and a battery to enable it to assist in landing and taxiing, as well as dealing with weather and the inevitable crashes.

I am aware that flying is the safest form of mass transportation but crashes do still happen and should be accounted for, after all, and it would be nice if the autonomous glider drone systems had a touch of brains in it to try to not land on a house or into a highway or something.