I do. I was brought up to say please and thank you to anyone.
Often these days, since I went blind, people will hold doors open for me and such. I always say thank you to such thoughtful people. I also make a point of thanking shop staff and people who work on reception desks. They get a lot of stress from their work so having done their type of work in the past I know how much nicer it was to get a customer who just said thank you.
And I always say thank you to colleagues and family, and even here on HubPages, I add a thank you to all my comments, it is just right to acknowledge people taking time to do something, even if it is their job.