You cannot expect an article to tell you these things.

Whether they work in Nigeria or not is not the issue. The issue is that they are doing it without compensating the country. Worse, they clearly don't intend to come back again (so you don't Ever get compensated at all, not just suffering time value of money) otherwise there's no need for a 5 year penalty. which is relatively huge compared to what the other countries are doing.

I guess sending money back home is not big in Nigeria culturally like it is in Mexico? Welp, I can't enforce you to send money back but guess what, I can enforce you to not leave at all.