Can confirm...wife started a franchise with a brick and mortar presence. I hold down the stable income. Also have the help of parents to look after our baby, as sometimes I need to help her on nights/weekends.
The same is true for other franchisee's we've met (1 remains the breadwinner). If you bought into an existing one that already generates revenue, then sometimes both spouses work there full time. But that means you need to have had $$$ in the first place.
We know of one franchisee who's wife is a stay at home mom. He quit his job to start one...less than a year with slow growth, he closed the center and went back to a traditional salaried job. He didn't pick a good location for exponential growth, but IMHO he had enough steady growth and would have been profitable if he could stick around for another few months.
One of you works a job that provides income and benefits for both of you, while the other works on a startup. Assuming most of what you need is a time investment, this is an approach that works for a lot of households to bootstrap.
Higher startup costs make it tougher though.