You are confusing things.
Assuming you are qualified, it is not difficult to get into a good undergrad school in the US. I’m not talking about Harvard or Stanford which are essentially lottery tickets for everyone, but your standard good undergrad is a realistic possibility.
You said you wanted to go to medical school. That is why you were linked an article about medical school. The article is talking about international students that have an undergraduate degree and are then applying to medical school. The article is not about applying to medical schools without an undergraduate degree.