One would wonder how criminals get their hands on drugs so easily. They're criminals.
More like they are easy to find because there are a lot available since the governments refuses the fix the problem because they are either afraid and/or stupid.
Maybe Mexico look at Colombia and think since they are in a better than them they don't need to change.
US and Canada have about the same statistics in drug trends. But regardless, your solution to violence is to take away the ability to defend oneself from millions of citizens because of the actions of a fraction of a percent of the population?
Enforce the hundreds of gun laws that are already in the books. Work on better communication between government agencies. Stop the revolving door of violent criminals being released back into the public to continue escalating their violence until people are murdered. Don't add baseless new laws when you don't even enforce all of the ones we have now. Start with that.
And Mexico looks at Colombia and thinks they don't need to change because they're better off than them? Ahh, I thought it was all the drug money and violence from the cartels that was corrupting them all this time. Nothing like citizens being beheaded and strung from bridges or body parts littering heavily traveled streets to send messages. I guess the message is that they're better than Colombia? An unarmed populace has no chance against organized crime or a corrupt government / government agencies. How do the Mexican citizens try to stand up to the corruption and protect their way of life? They create groups called autodefensas. Citizens arm themselves with heavy weaponry in open-topped trucks. They wear masks to protect their identities. They set up improvised checkpoints. It only proves that authorities have failed to establish order. No thanks.
Again, you cannot legislate evil out of people. Quit trying to impede on the rights of the good people and prevent them from being able to defend themselves. "Just doing something" is only going to hurt law abiding citizens like the millions of gun owners that make it through every day without killing people.