Ed,
RA-4 is a good-natured process. The tolerances for CD and BX are relatively high above the required minimum values. C-41 is much more critical in this case. It is the same principle as B&W paper vs. film processing

You won't need control stripes in an amateuer/prof. lab environment. You will see if something is wrong with your process and it will not be a huge loss if you have to reprint a picture. This is different in a minilab process chain where several prints go wrong until you notice an error. And if your print looks good, you don't care whether your process is within the standards. It's still photography - not rocket science ;-)

BTW: you don't use control stripes to check whether your Tetenal or Jobo chemistry has finished, do you?