In the US, they are legal under PL 170 and Immigration law. They present themselves to border folks, register and are given a court date to present their refugee or asylum claim, and many seek work. We desperately need more immigrant work in the US and to pay taxes and, especially, social security taxes since it is short of funds. Biden, with R's agreement, had a border deal to fund new judges, border folks, etc., to address the problem, but Dictator Trump ordered it killed in Congress so he could blame the Dems for not doing anything. He prefers chaos vs getting things done.
The illegal drugs are mostly coming in via the busy US border crossings from Mexico, Huge lines of cars and limited resources to search cars, need more drug dogs etc, but reports are close to 90% of drugs come in via the legal ports of entry not in non-controlled areas.