Wouldn't masons naturally like the building of walls?

I think there a lot of people who would profit from the wall(s) including some that some people might not consider as beneficiaries. Like Sr Gonzales of Cemex, which is obvious, but even criminals and the cartels. Price rises from making transport of certain drugs, sex trafficking, human smuggling, etc more difficult. Even the local independent coyote would benefit from the wall because he could charge higher prices. And making it harder for OTMs to cross means they might be stuck in Ol' Mexico and so available for use in the sex industry, illegal mining and labor, drug trafficking, or simply as gladiators in Cartel games or domestic workers. Maybe even for "parts" by the elites in Mexico (especially people coming from clean, rural regions who haven't, yet, polluted their bodies.)