The first time I ever referred to a professor as their last name (preceded by a title) was my first year of college. Up until then, every single one of my teachers had asked to be referred to by their… actual name.
For some, this may sound absurd. For others, the opposite sounds absurd.
In my opinion, you can tell a lot about the way a school runs based on whether the teachers ask to be referred to as Mr/Ms/Mx/Professor Lastname, or simply by their first name. Having some people in the room be given titles immediately puts a distance between those with and those without.
In a lecture-style education, such as often appears in college, this works fine. The problem is that lectures suck. Growing up with a discussion and participation based education has helped me learn in a way that actually sticks. Being able to talk to your teacher like a human, rather than like a higher being, gives you the freedom to ask dumb questions.
Whenever I talk to somebody that I refer to as "Professor", I first quintuple check my question before asking, and even then, I still pause a bit. Viewing the teacher as somebody who is at an equal level to you gives the freedom to just… talk. It's as though your friend was teaching you a skill they knew, versus your city's mayor.
I know that a lot of my professors in college say "You can call me Professor Lastname, or just Firstname if that's better for you", but there's just something about the college environment that makes it feel wrong to do that. Enforcing no titles, I feel, creates a better learning experience for everyone.