There are 2 different parts to this question. One is whether the student without advanced courses is at a disadvantage. The other is how common it is for attending students to not take advanced courses.
These are very different questions. Many high schools do not offer AP/IB/AICE/… type courses, and highly selective colleges often say students who attends such high schools will not be at a disadvantage. It’s difficult to evaluate whether this is true or not, due not not having adequate information.
What is more clear is that the students who attend highly selective college tend to take advanced courses. It’s well document that students who apply to highly selective colleges tend to attend HSs that offer many advanced courses. At such HSs, colleges expect students to take advanced courses. This does not mean taking every possible AP course that is offered, but they want to see applicants who take a rigorous course schedule.
Surveys of highly selective colleges, show the vast majority do take advanced courses. This is especially true at highly selective, private colleges, which likely have a larger portion of applicants attending quality HSs that offer advanced courses. For example, the Harvard freshman survey states that ~90% of matriculating students took calculus or higher during HS.
Anecdotally some of my family members attended a small, rural HS that did not offer multiple course levels – no AP or honors classes were offered. All 4 members were accepted to and attended different Ivy+ colleges or LAC equivalents (3 attended Ivy+; one was accepted to Harvard and Penn, but chose Swarthmore instead). They were clearly in the minority, among matriculating students. Most came from a very different background.