I'm sure it is happening currently ---- the Mexican army is still all over the border still. If they find Hondurans or Guatemalans or Salvadorans on their side of the border--- they will arrest them --- but they of course leave Mexicans alone after they look for weapons and drugs and money on them. I'm not sure why they arrest the OTM's --- because they know they're on their way to the USA and at that point they're close to leaving Mexico anyhow.
I studied in Mexico, stayed with families, traveled around a lot there. And I live close to the border --- and a lot of the problems of course spill over to this side. You can't avoid hearing about a lot of it. For example if something comes on about ending corruption in Mexico --- it's Mexicans who will immediately scoff at that and fill you in on why it's not going to happen. They say it's because EVERYONE is corrupt over there. It's Americans who are naive about Mexico not the Mexicans.