It's good that immigrants are seeking to become fluent in English, and you do point out that there is precedent with the government helping immigrants succeed in this, but--as with other things such as foreign and domestic aid--it should be voluntary donations footing the bill; alternatively, people can volunteer to help spread the language.
Some of the current ESL organizations are volunteer groups and some of them are for-profit schools that teach classes to immigrants on the side, while teaching execs as their paying business. However, having been involved with volunteer programs, both in literacy for black Americans and in ESL for non-native speakers of English, I can tell you that they simply don’t work as well as school or “official” enrollment programs.
For one thing, volunteers are nowhere near as dependable or as qualified as paid employees; for another, even the students don’t take it as seriously.
There are times when the government has to invest in something that is actually beneficial, as it did in the past. Make the students pay a little something (because this makes them more committed), but take the money from some useless nanny-state program and put it some place where it could actually benefit us all.