Yeah there is a reason, it's that the developers don't usually set aside public space, especially not in small quantities like that. If they're required to, they will typically lump it into one large park with something like a stormwater retention pond. They are trying to maximize lot size and not really think about pedestrian circulation.

Also, on the topic of North American cul-de-sac suburbs, I made a Twitter bot that is working its way through every census-designated cul-de-sac in America. Here's a good example of one with pedestrian access: https://twitter.com/culdesacbot1/status/1604474398442156033