There is also an education gap. For whatever reason, this type of work is considered extremely niche in North America and even if 100% of local ECE graduates were hired there would still be both a labour and skill shortage.
Also the majority of the people in the local education programs I've seen are also studying from abroad, so they need a visa once they graduate to actually do the work.
Its odd, since it is such a strategic industry, that there is not a more clear strategy here beyond just hiring abroad to fill the massive gaps.
In some ways these companies benefit from the extra power they have over their workers when they depend on employment for their right to stay in the country, but eventually the companies just end up looking like a less promising risk to take versus just going to work in other countries.