Most older i.e. pre-2000 era rigs have no way to stop fuel from running out on a rollover, some have fuel pump shutoff switches for oil pressure or inertia but that didn't stop fuel from coming out in a rollover so why the big worry about externally mounted cans?
I don't understand all the worry about this kind of crap or the need for all the government mandated nanny crap that keeps running up the cost of new vehicles because most of it is totally unnecessary IF the driver has any common sense, which is a dying trait I know but some of the world still has common sense, I know when I get a flat tire, need to watch where I am going in reverse and don't need my doors to lock automatically for me so I definitely am not going to worry about jerry cans rupturing!