Why does the U.S. import public school teachers?

I didn't know this was happening, until I stumbled upon this SPLC article. Louisiana is not the only state that does this,

• In 2009, these were the top 10 states in terms of the number of employer applications for hiring foreign teachers:

• Texas – 4,424

• New York –1,850

• California – 833

• Maryland – 828

• Louisiana – 694

• Georgia – 564

• Florida – 277

• N. Carolina – 261

• Virginia –188

• District of Columbia –170
source

Percentages count....Louisiana 9.5%, CA 1.3%, NY 6.4%, TX, FLA 1%

With all its resources and talk about how important the school system is to the nation, why can this country not produce enough teachers?? Why are we encouraging young people to "go to college" if we can't even encourage more of those same students to become teachers?

The article is about the abuse of these foreign teachers, but also read their PDF link.

Personally, I attended private schools (1950s-60s) and had a couple foreign teachers, but if US public school teachers nowadays are supposed to meet a much higher standard and test scores count more, are the foreign teachers equally qualified to produce the higher results?

Or are these foreign teachers imported in order to deliberately lower wage costs, as we see has been done in other labor areas in this country?

What is wrong with America that it needs to take in teachers from other countries, teachers whose own country needs that human resource?

Most ppl do not want to walk into a school where some of the students
have MS-13 written on the side of their neck.

Most ppl who go to school for long as teachers are required to now
can find a job that pays better as well.

I think we could take the out of work and put them to work as
teachers as some of them have the experience and or education
to follow a syllabus.

Most of what is taught now is determined from the top and the tests
are as well, and the teacher often just goes thru the motions.

From what I understand you see this in school disctricts that are short on teachers and unable to get American teachers to transfer because the schools involved are in bad areas. You have to get teachers from somewhere. I guess spending the money to clean up those schools is not an option for some reason.