How do you filter the people who hold the door for everyone vs the ones that are only doing it for ladies? Or for those fellas who where told countless times as a youth to hold the door for a woman. Because someone is polite, that is a red flag?
As for calling a woman a lady this one is new to me, and I don't think I've ever used the word "colleague" aloud in my life. I would say, "that is a {guy|lady} that I work with." I've never been made aware previously that referring to a woman as a lady would be taken negatively. I had only heard that some woman don't care for ma'am as they can feel that is a title for an older woman. fwiw, I do tend to use gender neutral words like "they" or "them" over he/she when writing.
"Person" also works in this case. +1 for they. "Lady" seems patronizing to me - would you call someone a "gentleman"? To me, "lady" describes a woman who is "traditionally feminine" – I get that when people use "lady" today they don't typically mean "traditionally feminine," but "lady" is still evocative of a time when women were seen as delicate/demure/less than men.
I think it may not be a good idea to draw conclusions from this without seeing if they do the same for guys too (which you may not be able to observe during an interview). In my workplace everyone pretty much holds the door for everyone else if they're walking in a group. The first person who gets to the door will open it and stand behind it while the others walk in first. Sometimes we'll throw in a lighthearted "after you" too. I'd really hate for someone visiting our company to get the wrong idea about our culture from a common courtesy, especially in an interview scenario where the interviewer may just be trying to be nice to the interviewee regardless of their gender.
The same thing happens often in trains, where sometimes as a man you get snarky comments or disapproving looks from other passengers for not jumping up to "rescue" a woman that dares to put her luggage in the overhead compartment all by herself. Would be curious to hear how women here see this but I always think that people are able to ask for help if they really need it and that automatically assuming that they can't put their luggage up by themselves is degrading to them.
Sorting people by gender and age when going through doors or out of an elevator is also silly and degrading I think, so I can understand that you don't want to work in such an environment.