hmm, this is one of those things that is hard to know
on one side
being a sahm doesn't give her lesser rights - she should be respected as an equal
using a car for domestic chores benfits the entire family - including him - so why shouldn't she have a decent car?
if they can afford it, it's quite mean spirited to refuse her the money, unless she's spent an equivalent amount elsewhere
on the other side
it's expensive to buy & run, so why spend money unless they need to
it may well end up being scruffy, so why buy a 'naice' car for kids who don't appreciate it
prob it's more the fact that he won't 'allow' her the money, as if she somehow has to earn it before being rewarded. perhaps give him a bill for housekwwping, childcare, cooking, shopping etc. then when he pays you the money, buy your own car with your earnings?
it still amazes me how many men just don't get how much better off they are because they have a wife who is supporting them. Yes, the cash they earn to come into a family is important - but so is the work of the housekeeper/childcarer etc. Either they're willing to pay for those things (either a nanny, cleaner etc, or being supportive & sharing of a wife) or they have to accept that they don't get food, housing, children, etc I mean children don't magically grow up unaided, houses don't clean themselves, the food fairies don't put dinner on the table. Somewhere along the line people have to produce or pay for it. He can pay by hiring people, or pay by respecting his wife & buying her a car just cos she wants it, and he loves & respects her.