That’s surprising to me. It has been very common in my experience. But note that I’m specifically talking about interviews for entry level positions. The questions you listed would be typical for a position requiring experience, but kids coming out of school don’t usually have much practical experience. The questions in those interviews tend to be more theoretical, out of necessity, at least in my experience.
Algorithms questions are definitely less common as you get further in your career, and less common for front-end type work. In my experience, more often than not, if the position is more of a core developer type role, as opposed to front-end, you’re going to get at least one guy who will beat you up with either writing or analyzing an algorithm that you would typically see in a Data Structures or Analysis Of Algorithms course.
The more technical and more academic the company, the more likely you are to see those types of questions. I mentioned those types of questions because that’s where the interviewer is going to see the biggest difference between the OP and the candidates with CS degrees, unless the OP self studies that material.