Simple economics , tow bar less tugs are very expensive, which is why you still get pushed by ancient tugs in a lot of places ! Ref headsets , you cant use them when theres a lightning risk so if your airline doesnt allow handsignals then i guess you take a long delay............
Not really soo simple, the towbarless tug does not require the massive deisel engines conventional ones do, reliability is greater maintenance costs are less. We love them at our operation. We increase efficiency by not running that big diesel to go get a different towbar for a different type jet.
The only thing unsafe about pushing yourself is having to get out to disconnect the headset and bypass pin thus we use a 2 man crew. some insist on walking a wing, I believe this practice only need to be used when "ground handeling" people are doing the job. I don't trust them as it is not a career but just a job to most of them.
It is an international standard to drive behind an aircraft with a beacon on at your own risk, you deserve a chewing out if you attempt this after pushback has commenced.
The towbarless tug gives great visibility and control, I would consent to a one man operation if there was a way to remotely remove the bypass pin and headset chord, or a wireless option.
I personally hate having a wing walker, just another liability. Back in my flight mech days we ran over a guy on a headset down in san Jose Costa Rica with a DC-10-30. He got tangled up in the headset chord and fell behind the NLG in a turn, 2 pices of the poor kid were left and probably about 30 lbs of ground-rican about 5 feet long/nose gear width wide.