The only way “Cubans” would be doing land-crossings like Mexicans et. al is if they’re NON-Cubans aware of the special, “dry foot on land” rule for Cubans, and are simply LYING about it.
The O did away with the “wet foot, dry foot” policy. It still doesn’t make sense for them to come this way, but indeed they are and have for the last few years.
Everyone comes across this border. We need a wall and we need to be able to enforce our laws.