First, They make all the ATM's the same.. they would need to go out of there way to remove the Brail from a drive up, since they do have to have it on the walk up. Another production line, costs more money
Secound, Most cars have this little thing called a back seat.. a Blind person does not need to DRIVING to use the drive up ATM
Third , There are differnt types of blindness.. It is possible that a person wouldnt be able to read the ATM screen... and need to use brail, but still be perfectly fine driving.