I've previously written about this very subject and recognise that some dads have undoubtedly failed to pull their weight (which has sadly been your experience). However, I'd argue that isn't the case for the majority. And where dads aren't playing an equal role, often that's been presented as the status quo by society.

In the UK, the default paternity leave for dads is 2 weeks whereas mums can take up to a year. Shared parental leave is available but there has been low uptake (I wanted to but my wife and I weren't in agreement on this). Then there are the media perceptions of dads as being the inferior parent and everyday ignorant remarks that reinforce dads being incompetent parents. This in no way excuses dads who aren't pulling their weight but it provides some context for how some dads have arrived at this as the status quo - which I fully agree dads need to refute.

In my own experience, my wife and I share all responsibilities. I am no less of a parent than she is in involvement, effort and taking responsibility as a parent. And many dads I know do the same. Where that doesn't occur to the extent that it should, I've seen where it isn't for want of trying. Some dads want to do more but get push back from mums who resist their involvement due controlling the sphere of parenting. They see it as almost exclusively their domain on account of being a mum (again, society pushes this). That's only to later lament that their partners aren't pulling their weight.

I hope the father of your children does become more involved and that he shares the load and effort as it should be. This is a necessary conversation that needs to be heard to address the inequalities that can still be found in parenting.