With all due respect, why in the world does 28k sound like a reasonable number for care of a single child? That's more than many people make at a full time job.
With reasonable overhead numbers (space, management, compliance, licensing, taxes, etc.), that's a poverty-level income for preschool teachers.
There is a strong argument for subsidies, at least in countries which have low birth rates and care about longterm social outcomes.
Regulations prevent that, and kill the free market. Now everyone pays a crapton to some facility where the owner jumped through all the hoops to get certified, while hiring minimum wage people to care for the kids. Not that some aren't great, but is it really a better system?
The longterm costs of that -- crime, mental health, etc. -- explain why subsidies make sense. Every rich country has universal public education for a good reason.
Market forces, as you point out, will drive your enterprising person making 72k out-of-business very quickly, and the market becomes a cesspool.
Childcare in the US is way more expensive than it should be. The costs are also highly location dependent with the coasts being much more expensive than the Midwest etc…