of interest:

"And I wonder why the artists, who painted in many antique plots, Mercury, gladiators and biblical characters in gladiator sandals missed such an important detail as socks?
Per, the paint saved"

Apparently, for the same reason that the Vikings are painted in horned helmets – for lack of information.
The Roman Legionaries wore socks under their sandals. This conclusion was made by scientists who carried out excavations on the site between Limming and Dishford, in the English county of Yorkshire.
Found by researchers on a nail that attached the parts of the shoes, fragments of fabric were evidence that the Romans wore socks (or something like socks) under the sandals. Similar samples of fabric were found in 14 other tombs of ancient Romans.
You will have to experience this news somehow and learn about Google.