A shop=forcourt is a shop found on a garage forecourt with the primary purpose of paying for fuel. They usually sell minor spares such as oil and bulbs along with crisps, sweets and pop for the journey so not a destination shop in its own right.

As confusedbuffalo say the majority are mapped as shop=convenience, which in recent years most have become as the lines between shop types have become more blurred. That tag implies that it is somewhere to go food shopping. Traditional forecourt shops are not that place.

Community discussion on #osm-gb has resulted in whether a place whose primary purpose is to pay for fuel should just be part of the amenity=fuel and just mapped as building.