The Schrader valve retreats back into the inner tube because there is nothing to hold it in place against the wheel rim. Despite having an outer screw thread on the protruding valve nothing is there on that thread, apart from the valve cap. When the pump is applied it pushes the valve assembly into the tube making proper connection for pumping difficult and even damaging the inner tube as each stroke of the pump handle causes the valve/pump connection to move against the metal of the wheel rim.
Back in the day every Schrader valve had a retaining nut/thumbscrew to keep the valve stationary -- rock steady -- while pumping the tyres. If this omission is now standard it is a retrograde step and I want all of my valves to have a retainer nut/thumbscrew to avoid damage and make pumping much easier and more efficient. Are these available? How did this crazy change come about?
Yes, I am an oldtimer and my earliest cycling days were at school in the 1950s.