Actually I rather disagree with you. The 'standard' entry to a deliberate inverted spin requires full fwd stick and rudder. All any spin requires is asymetric stall - usually yaw and a suitable angle of attack, same as people still manage to spin into the ground, without doing a deliberate spin entry.
for example - here's a little inverted spin scenario:
Rolling off the top of a loop - you're a bit slow, a little hamfisted, and you forget that with negative alpha you're effectively cross controlling as the adverse yaw is reversed... trying to hold the line, and...
Oooppss! the world suddenly rotates..
Hopefully you're smart enough to catch it at the incipient stage, but if you're already head in/singular focus, who knows.
Of course inverted all the anti spin design features like washout are working against you.. so it's arguably even easier to spin inverted.. and in some types, mishandling the ailerons etc can turn an erect spin into an inverted spin.
For that matter, you don't even need rudder to spin - I've seen (deliberate) spin entries off adverse yaw/aileron use at stall (in gliders, granted).
So if you have a change get out there, jump in the suitable aircraft with somebody who has practice and go demistify the whole manoeuver !!!
Call me paranoid, but I did - last week. Damned unpleasant it is too - I enjoy spinning sunny side up, and do basic aeros regularly but the flick-upright-bunt-over is somewhat confronting, and a little disorienting. My lunch *just* about survived.