No, and if that's how it is, you need to talk! These things can get tricky - seems a lot easier when things are the traditional way round - man earning more. I can imagine there are a lot of egos and awkwardness if the other way round.
If you have children, then you are a team! My OH earns twice what I do (so three times more while on mat leave) and I find it difficult to ask him for things as this is the first time since in 23 years (since my paper round and commis waitress job at 14!) I've had to be more reliant on someone else. Mortgage and bills are paid 50:50 (and it's important to me that I pay my share, although that is almost all of my mat pay) but that's my problem, not his. I get the weekly shop once a month and he gets in 3 times (again - getting it in once is at my insistence, can't afford anymore).
If I need anything for Sam, my OH gets it - not prepared to let my principles affect him (although I did pay for Water Babies with my credit card as thought this was a bit frivolous!)
If there's enough pettiness for her to try to stop you driving, what's stopping her making the payments and leaving you with a CCJ against you? Be careful'
Oh! Gotta run - he's stirring, and not fed since 11 as had a mammoth, unexpected nap!!