None of those benefits came close to the cost of the program

How do you measure the cost-to-benefit of longer maternity leave? Or higher high school graduation rates? Not everything the government does needs to directly make a profit. Just look at roads for an obvious example of that.

once initiated productively decreased. Likely would have even decreased further but people knew the free money would eventually end.

There was only about a 13% decrease in hours worked for the entire family on average, and most of that was women going back to work after a pregnancy later and teenagers not working (probably so they could keep going to school).

How do you pay for a program when the local area taxes don’t cover it particularly when the tax income actually decreases once instituted?

It’s not about Canada, but you can always find a way to pay for things if you really want to, even if they’re objectively bad for tax income.