The higher end Trek bikes you are describing probably use the Bosch Performance Line motor. This motor spins the chainring 2.5 revolutions for every revolution of the pedals. Also, the pedal input to a separate gear from the motor/chainring output likely makes it easier to sense the torque of your pedaling.
Most electric motors naturally want to spin faster than you pedal. You will often see geared hub motors with gear ratios of at least 5:1. The faster speed allows the motor to be smaller and yet still efficient.
That's some technology! Thanks for the helpful info.
As my rear hub motor makes repairing flats more frequent and complex, the idea of a mid Bosch motor sounds even more appealing. Someday...
