Do blind people have to memorize all surroundings perfectly?

No, they don’t have to.

Generally, in addition to their memory, they use their senses of hearing and touch, and develop practices of paying attention to those and moving with confirmation from them and/or in ways that don’t over-commit so bad things are less likely to happen if they start to go someplace problematic.

They can also use the assistance of tools such as canes, or helpers such as trained dogs.

Oh GOD no! I mean, I’ve worked on three continents and currently live in New York. Could you imagine the mental load if I had to memorize, say, Aachen in Germany before I went to work there for a week? And, I mean, how the deuce would I get around in the meantime? I use Google Maps like the rest of you. The only difference is that, in lieu of reading street signs, I have a GPS app that announces intersections and points of interest.
... Actually I have about five of ‘em, depending on what I need at the time.