Why do they make 24 volt cars?

Why do they make 20 volt cars?
I was thinking about this the other night because a buddy of mine had to wait in the parking lot at work last night for 3 hours waiting for AAA because his battery was dead and no one could jump his car because it's 24 volt. So that got me thinking, why do they make 24 volt cars, it seems like it just an inconvenience. Does a 24 volt car have any benefits. His car is a Ford Taurus. Ps. I asked this question a few hours ago but I put 20 volt instead of 24 by mistake.

Most military vehicles and some commercial use 24 volt systems.
ford did think about going down that route but customer feedback stopped them
reasons are. More voltage means more power availability for starting motors and smaller cabling used in cars etc.
car used to have 6 volt systems but low voltage didn't assist starting and batteries often had to be supported by hand cranking an engine on cold days.
when it was made 12v.hand cranking ceased to be needed.
with 24 volt heavier engine cranking loads can be used. E.g. Multi cylinders. High compression diesels etc
ideally all car manufactures would switch overnight if it was both economically easy and customers got past the 12V hang ups.

Your buddy is still wrong - there's no 24V Ford Taurus.

That 24V badge on a Taurus indicates 24 valves, not 24 volts.