It's not necessarily any lack of power/torque for towing with electric vehicles it's a problem with type approval and an issue regarding associated systems coping with extra stress.
For example you average ICE tow vehicle will weigh around 1500 kg. Stick a ton behind it and your gross train weight is still within fairly safe limits for brakes, suspension etc...
Get that same vehicle in EV form and it will be around 500kg heavier. Yes, range will be severely affected but its likely your Gross train weight is above acceptable levels for brakes.. Hence type approval issues.
For example you average ICE tow vehicle will weigh around 1500 kg. Stick a ton behind it and your gross train weight is still within fairly safe limits for brakes, suspension etc...
Get that same vehicle in EV form and it will be around 500kg heavier. Yes, range will be severely affected but its likely your Gross train weight is above acceptable levels for brakes.. Hence type approval issues.