It varies from country to country, and company to company. However typically the globally integrated oil & gas majors such as Shell tend to operate 25-35% of their sites and the remainder are on various forms of franchise arrangement. Franchisees can range from mom'n'pop singletons to quite large multi-site groupings. Typically supply of each geographical cluster can be largely (but not exclusively) traced back to a refinery in each region (or pipeline terminal) that act as the distribution hub, though that can be complicated by various swap arrangements with other suppliers. The entry of the various grocery/supermarket chains into petrol retailing over the last 40-years has upended the business in many ways.
The sites themselves (as opposed to the operatorship of the sites) cover the whole range from wholly owned - long term leases - shorter term leases, and to an extent that has been a factor that was somewhat independent of who had site operatorship.
As we are all well aware this business is now being completely disrupted. Some of the requirements are mutually exclusive (for example I never expect to see a combined petrol/gasoline dispenser and a electrical connector), but others are quite complementary for some of the use-cases (toilets, convenience stores, fast food & beverages, land ownership/control, location).
Tesla currently (Q3 2021) has 3,254 charging stations and 29,281 connectors. It is reasonable that the high-case for Tesla in 2025 would be 30,000 locations and 270,000 connectors all of which would be high power fast connectors (not what Tesla would term a destination chargers). So this announcement indicates that Shell is seeking to remain relevant in that part of the value chain, i.e. at least they understand the scale of the challenge (500,000 points). However one needs to read both the Shell and BP press releases with highly cynical eyes as I am pretty sure that Shell and BP are counting slow street-kerb-located overnight chargers in this 500,000 target.
I am pretty sure I did a post about the economics of a typical petrol/fuel station using Shell vs Tesla as a comparison here on TMC a year or so ago but I didn't get much feedback. That was a shame as I was trying to flush out some hard data re Tesla Supercharger usage statistics to take the analysis to the next level. Can anyone see it ?
(Once upon a time I worked in upstream O&G, but because of some oddities I had some interesting engagements with the downstream (outlets) and midstream (refining) organisations).
EDIT: aha, found it - see
Supercharger network - capacity & valuation