Chalk and cheese!
A piston engine cannot idle at much less than about 600-800 rpm, unless specifically designed to do so. There is therefore no point in trying to take it slowly; if this were done there is a good chance that the engine could kick back, damaging the starting gear or the crankshaft, especially if there is a heavy propellor on the end. The starter motor is therefore designed (big current draw for a short time) to kick it straight over compression from where it should fire and go straight up to a reliable idle speed. Once the engine fires, the starter kicks out of engagement.
A turbine engine relies on a smooth, steady gas flow being established through the combustion chamber and the rest of the unit before fuel can be introduced, to prevent a hot start. The starter motor (often also the generator and thus remaining in mesh with the rest of the engine) is therefore designed to give a smooth, steady acceleration to a speed where initial combustion can take place and subsequently to continue to assist in the acceleration of the compressor towards idle speed, often close to 30,000rpm. Due to inertia, this cannot be done instantly.