The garage is used by my husband. It is intended for his motorcycle.
The other one of my steel garages - both uninsulated, by the way, so "stalactite caves" - stands on strip foundations. The others in the row even have ash floors, but several "generations" of previous tenants of mine were motorcyclists, so mine is laid with paving slabs. Flawless, without breakage, without subsidence.
Of seven garages, I had only one with a concrete slab, this garage was solidly built with bricks. The others, even with concrete floors, had only strip foundations.
I consider shuttering blocks to be the most practical option for DIYers.