PET 2001/2001N can "write" to ROMs

Hi all,
Ok, the subject is a pun, but write is in double quotes anyway. I was
wondering why the PET (at least the 2001 and 2001N, the ones I have),
leave the ROMs selected during a write cycle on ROM space. This of
course makes a data bus contention because the selected ROM will drive
the data bus and the 6502 will drive the data bus too since it's on a
write cycle.
I wonder if this can be a factor in the high failure rate of the old
6540s and the newer 2332/2316.
It was just lazyness/cheapness or do I miss something?

Frank IZ8DWF