Frost apron - advantages and disadvantages

Hello everyone.

Can someone list the advantages and disadvantages of a frost skirt?

Why are some houses (ours, for example) built with a frost skirt, but many with a normal slab?

Depends on the ground, with poor load-bearing capacity like sand and clay, frost protection is used.

It depends on the soil; for poor load-bearing capacity like sand and loam, frost protection is used.

Sure?

Best regards

Frost skirt belongs under every slab, is often omitted for cost reasons, usually nothing happens.

Hm. I have not experienced that it is omitted. My understanding is that every foundation requires frost-free footings.

Have not dealt with it at all. What is the function of the frost skirt? What characterizes it, insulation up to x cm into the ground?

We have a continuous strip foundation without insulation and some insulation under the slab.