I think most success stories have an element of “who you know” and kindness. The “who you know” doesn’t necessarily mean that you know someone in a place of privilege either. Look at what’s-his-name from a few seasons ago who went off and became a chef. Mrs. Padmore and the rest of the staff pitched in to help him with that. Then there is Mr. Mosely helping Daisy with her studies. And, yes, Sybil was in a place of privilege, but I believe she would have helped Gwen even if they were both housemaids, because that’s the sort of person Sybil was.
I’m guessing we’ve all had friends somewhere along the way that have helped our careers or that we have helped. When I needed to change jobs, I reached out to someone I’d mentored as an intern who was now in a different part of the company. He helped me move over to a new position. I’ve helped others with tips about positions that I thought fit them. I do this for people that I respect, but also that I LIKE. I wouldn’t recommend a Thomas for a job even if he would be perfect for the butler position in my neighbor’s estate — cuz he’s a jerk. (Of course, lots of jerks seem to get ahead anyway, but that’s a whole other discussion.)
So, yeah, you can probably get a different level of assistance if you know someone in high places, but those aren’t the only people that can help you out.