You will only get a voltage equal to the turns ratio times the input voltage if all the magnetic flux on one coil goes through the other coil.
That can never happen, so the voltage will always be less.
In a transformer, the coils are very close and it is very difficult for magnetic flux in the primary to avoid the secondary, so the voltage is nearly the theoretical value. It will usually be between 99% and 100% of the theoretical value for a good transformer.
In the drawing you show the coils are far apart. Very little of the flux from the primary will go though the secondary. Also the angle of the coil is set to give very little voltage.
When the railway wheel passes, the flux changes angle, so more flux goes through the coil so there is a bigger voltage.
The coils are not designed to transfer power, so they are bad at tranfering power. They are designed to detect railway wheels, so they are probably quite good at that.