It does appear that McD’s owns a lot more real estate than most other fast food chains. Based on a quick search of balance sheets, 67 percent of McDonald’s assets are “fixed assets”, which I would presume is mostly real estate. Fixed asset figures for Wendy’s total 36 percent, and it’s 32 percent for YUM brands and only 4 percent for Dunkin’ Donuts.
I am familiar with Net Lease properties, and you’re right that it is fairly common for the real estate to be owned by a third party - neither the chain (franchisor) or operator (franchisee). But it appears that McD’s does own more of the underlying real estate than most chains. They serve as landlords to a significant number of their franchisors.
Franchisees are McFree to open some other fast-food place if they don’t like the terms of McDonalds’ franchise agreement. The reason McDonalds owns so many of the franchise store buildings is that their franchise fees are extremely high, and franchisees get better terms leasing the land from McDonalds than they would buying it subject to a commercial mortgage (not to mention financing the cost of construction).
Big Boy is kinda sorta doing the same thing. As a result a lot of Big Boys have closed in this area. (Older owners not wanting to pony up that kind of scratch when they’re looking at retirement too.)
I would recommend the film “The Founder”, which explored how Ray Kroc realized that the real money was in owning the land and leasing it to franchise owners.