Why do heavy vehicles pass through the swampy terrain, through which a person cannot pass?

The determining factor in passing through a marshland is the pressure P, with which the body presses on the surface of the marsh.
Pressure P is called the ratio of the force F, with which the body is pressed against the surface, to the area of this surface S.
P = F / S.
The area S of the sole of a person is insignificant, so the pressure P becomes large, and the person begins to sink into the swamp.
Heavy machines, usually tracked, have a large contact area with swampy soil, which means the pressure will be small.