O.P. I totally get where you are coming from!
Here in the U.K. Slotted and Phillips always used to be the same colour, but when Pozidriv came along (which was a great success here) the makers realised that that they needed to do something to distinguish Pozi from Phillips. Blue was generally used, and the practice continued till fairly recently.
On my bench I have Slotted, Pozidriv, Phillips, Torx and both Inch and metric hex in regular use! I always distinguish Phillips from Pozidriv as that gets you every time, but when I start on a bigger job It’s useful to colour code the rest too!
PB Swiss, even with their Classic or Multicraft hard handles, put green handles on the Pozidriv, which is a start. They colour code their bits to a degree too, but they do things like making Torx a different colour from hex, when I can see they are different, but make Metric and Inch sized hex bits the same!!!
Making the different sizes of slotted driver different colours is totally pointless - I can SEE they are different sizes. They have yet to colour code the different types, which is what we all need. The colour coded caps on the soft finish drivers is something, but those drivers are the least suited to most workshop environments!
You can, just about, achieve what you want with Snap On, but you have to do a lot of swapping aound yourself, which can be costly. Neither Snap On or PB seemed to be tuned in to what the customer really wants, or how they work.
Facom offer decent colour coding on their current drivers. I’ve forgotten what they are called but suspect they are half decent.
Irazola Tekno drivers (spanish) were totally colour coded. I have a few and they are decent, but you are back to soft handles again. Same drivers are now marketed as ’Bahco’ Tekno