A few things seems to help, although there certainly still is some discrimination (in certain jobs especially).

1) All your competitors have to follow the law too, so it's just another cost of doing business.

2) Women are having children later, generally, so employers will see a 25-year-old and think "eh, I probably have 5 years at least".

3) Men are starting to take more parental leave, and the law is mostly gender-neutral (there is some amount of leave specifically for mothers who have given birth, but most can be taken by either parent). In fact, both parents can take the leave and have their jobs protected, although you can't double-dip on the paid benefits. I took three weeks off at my daughter's birth and 3 months when she was ~9 months old.

4) Maternity leave coverage is a great way to try out an employee for a year - hire Jim to cover for Jane, if you like him keep him on after the year, if not he disappears. (Part of this is Canada is more resistant to the contractor/employee trend than the US).

5) The people doing the hiring are likely to either have children or will in the future, so they feel like it's a reasonable/good policy.

Nothing blows my mind as much as hearing Americans talking about maternity benefit. I was listening to a podcast and one person said "we were lucky to have such good maternity benefits, I didn't have to go back to work for 6 weeks" and I was floored.

A candidate may get pregnant between the ages of 20 - 40. About half the people in my social circle with kids aren't married and almost all had their kid(s) after 35. This is quite a definite trend here in W-Europe.

Here in Belgium maternity leave is actually quite short, but you have the option to extend it for many months albeit at a reduced pay (provided by the govt). Not everyone can afford to extend it. Dads can also get paternity leave, up until the kid is 12yrs old.

Gender roles are changing a lot, paradoxically me as the father / chauffeur of the family is the one who has to leave by 5:30PM every day to get to day care on time while my partner doesn't have that limitation on her working hours.

This is totally a wild guess, but I think a small part of it is just the cultural values. It seems most people are for such leave, including the people who hire.

I would argue that it's not the law that's preventing discrimination, it's the fact that nearly 50% of the workforce is made up of women, thereby excluding a huge category is detrimental to your business. You wouldn't be a very good manager if you decided not to hire women because one day they might take a year off. Additionally, many managers are probably also parents themselves and understand the importance of maternity leave and understand it's part of having a workforce. Plus, in my department, we actually see the benefit of maternity leaves. We get to hire a new person for a year that can bring new insight and experience into the role. If they are good, we try to find a place for them, if they are bad, the year expires and they go off without any fanfare.

I believe quite contrary to the other responses you have received, it's not about kindness really, but mostly a function of where it would affect people the most and how those companies operate and are formed: through a very small circle of friends who know each other and because such companies are in minority such discrimination would be quite invisible whereas Big Corps(tm) can just eat such costs quite easily and they are held to the standard of hiring more. Smaller companies (that require higher education or good thinking skills) also probably get people who care about their career more at that point, getting kids at a young age is pretty low education thing to do (just as a statistics on who gets kids and when) and those people work in very gender separated fields usually.