it’s actally not allowed to drive in slipers.
i do drive in trainers too,and have Caterpillar Safetyboots next to my i wear by entering a yard were i have to waer it.
It is not legal to drive in bare feet, even with socks. It is also illegal to drive in shoes without a back strap or raised heel.
I normally wear soft shoes or sandals for driving and keep a pair of safety shoes somewhere under the bunk 
At last though I have discovered some lightweight steel toe cap sandals that I must buy just to wind up these powerstruck pompous H & S men 
When I was driving tankers, I wore wooden clogs and never had any problem running up and down the ladders