Chris - as you guessed, it all comes down to speed. TV screens are scanned at much slower rates than even a modest analog scope. The lower scan rates allow for magnetic deflection (coils on the outside of the neck of the tube), which would generally be incompatible with fast deflection speeds. CRTs in analog scopes used electrostatic deflection (deflection plates inside neck of the tube), which lend themselves to much faster drive frequencies.
As for calibration adjustments in the analog scopes... There are a lot of variables that enter into the accuracy of the analog scopes, mainly due to the multitude of circuitry between the front panel connector and the deflection plates (attenuators, preamps, amplifiers, offset control circuits, drivers, final amps for the plates, etc. - and that's just a portion of the vertical analog path). Each of the analog circuits will have offsets, non-linearities, etc. that need to be zero'd out to calibrate the response). Similar adjustments would be need for the horizontal and trigger circuits.
By contrast, the digital scopes are much simpler. There is some analog conditioning circuitry between the front panel connection and the ADC (analog to digital converter). Once the signal is sampled by the ADC, any calibrations adjustments to the signal can be applied digitally before being displayed. Thus, ALL of the complexity of amplifying the signal to drive the deflection plates of the scope is gone. Basically all of the calibrations and corrections are applied to the sampled data numerically after the data is sampled using calibration data installed at the factory.