The days of physical strength being a requirement to fly an airliner should be well behind us by now. The B707 demanded a fair degree of exertion from the PF, particularly in the case of engine failure or loss of rudder boost and the check rides looked for this. If you couldn’t supply the required force to make the aircraft perform as required then you didn’t get it on your licence.
If the B737 trim wheel requires strength in excess of what could reasonably be expected from anyone who holds a class 1 medical then the licence holder must demonstrate that they have the capability to turn the wheel as needed if they want the rating. Alternatively a powered system with the required degree of reliability and redundancy could be fitted and the manual back up done away with.
The trim wheel on the A320 is only used to input the take off setting and wouldn’t be touched again unless the FBW system degraded into mechanical back up mode. This is a last resort and only meant to give some degree of control whilst a flight computer can be reset. Even this requires hydraulic power to work so strength isn’t needed.