You got me very wrong there.
I am the original, Left brain, disorganised slob.
Flat surfaces are for putting things on that you never seem to get around to putting away.
And no you don't get every last drop . I checked a few times, probably around 1 to 2 oz left in a ride on Briggs engine. Kohler & Honda drain almost clean.
Then again you never get the last drop with a drain pan. it will drip for hours, which is one reason why flushing oil was invented.
It is a time thing. It is quick and convienant, just so easy to pull the plug and pour the spent oil into the old 44 I keep the dead oil in.
No more fishing around in an oil pan looking for the dropped drain plug. no more accidentally tipping the fresh oil in before you put the drain plug back.
No more hurt backs from picking up push mowers and holding them upside down over a drain pan. or overalls covered in fuel because you forgot to drain the fuel tank before tipping the mower over to drain the oil.
Cleaning up oil spills is no drama except it takes time and that is non-billiable time, costs money for shop rag, is messy and disruptive and then there is the OH&S problems of ending up with a boot full of hot oil.
I work alone so work in a very disruptive manner as I am always opening the gate or taking phone calls so anything that eliminates one "forgot what I was doing" mistakes is a good thing for me.
The tradeing name is Berts Mobile Mower Repairs so yes I also do on site servicing & repairs so it looks a lot better in a customers yard to be pumping the oil out cleanly.
Neary all of the pumps I have sold go to my commercial customers, those who change oil in something every week.
Home owners don't want to spend the money but I have sold a few syringe type oil pumps to householders.
OTOH I have sold better than 30 of the small 2 litre ones to BSA club members.
If you think oil changes on a mower is messy, try doing it on an A65.