I get my Global Entry (which includes TSA pre-check) for free through my Chase Sapphire Reserve. I never thought I'd have a CC with a high annual fee, but the perks more than pay for it - lots of miles, global entry, $300 in travel credit yearly, entry to airport lounges, travel insurance.
I've flown with my SO many times on the same reservation. He does not have pre-check. He's never gotten it free. Once we were concerned that he wouldn't make it through security at MCO as there was a much larger crowd than the lanes open could handle. I took his bag through the precheck line since I knew what was in it, so he could walk through the regular line without having to deal with the backup due to bag checks.
Strangely, at smaller airports, he has occasionally made it through the regular line quicker than I made it through the pre-check line. This is usually due to people having been given pre-check free and not knowing the procedure, thereby holding up the line for everyone else. Ugh.