This is an area where more research is needed. But this is an interesting paper by Bashir and Luque: "Equity in Tertiary Education in Central America: An Overview."
The authors miss an important point of the supply of higher education: they do not talk about the barriers to entry in these countries. Take the case of Guatemala for example where a Board that includes the existing universities approves new entrants (very odd!). It can take years to approve new entrants, like five or six years. And if you want to launch a purely new online university, good luck, the legislation does not know how to deal with that. Of course there is the issue of quality, but again the barriers to entry are enormous.