Not sure what you mean by saying that using a throttle is faster than pedal assist.
@jimix Every e-bike and rider combo is slightly different, different chassis, and rider weights, different wheel and tyre combos, skill/style, appetite for danger, different ECU controller max power and assist settings, ECU comfort delays, etc. When every millisecond counts ie. crossing an open gap in traffic that will close again - one generally wants to commit the full power available to clear that collision zone asap. Waiting for the crank magnets to signal the ECU that there is peddling detected and then to phase-in power over a few crank cycles might be comfortable on a Sunday in the park, but it can be too slow at the cross street downtown. eg. Our household has an e-bike with pedal assist that comfortably spools-up PAS gradually over 5 seconds - too long. In those cases (which can be often in an urban environment) overriding with the thumb throttle wins every time. The thumb throttle allows instant torque acceleration to get well underway through the danger zones, before the foot that was on the curb has rejoined the pedals.
Note also that the max available battery power, the power assist onset, and level settings are often preset at factory at levels well-below the maximums, usually around 75-80% of what might be possible on tap. This is manufacturer set reserve capacity is intended to extend product longevity for widest possible variety of general consumer uses, topography, and rider scenarios - but mainly, to preserve the hub motor from burnout with heavy riders using thumb and/or PAS on long hills (those hub motors can get so hot that they risk catching on fire). It may also be to meet regional e-bike class compliance.
Nevertheless, if the rider doesn't have hills in their ride, lives in a temperate zone, and actually contributes with pedals more often than not, then the rider can probably opt to go into their controller settings mode and carefully crank up the parameters for max available power for thumb use, and tune the factory onset delay of full PAS...among other things. Whether the rider wants to exceed speed rating of the permissible class should be up to their assessment of risk. Manually arrowing power level 3 for 20 mph vs power 5 for 23mph+.
As m@Robertson suggests, max power capability doesn't need to necessarily translate into more dangerous. True also that there are e-bikes that have foot pegs instead of pedals, and briefcase-sized one wheels that can do 50mph. Those are different animals and maybe should be classed/licensed as motorcycles/mopeds and stay out of the municipal cycle lanes...but that's not my fight. Sorry for the lengthy Cliff Clavin.