Nobody had even a proof of concept for a shoe that looked like a running shoe on the outside but had "springs, wheels" inside, so the officials didn't need to. Compare it with competitive cycling, where for a hundred years officials didn't need to X-ray the bike to check for hidden motors, but now they regularly do [0].

If the Nike shoe is banned from professional competition, athletes will stop wearing it, and officials will investigating other shoes for carbon fibre inserts, and will likely catch some. They're not stupid.

[0]https://cyclingtips.com/2015/04/hidden-motors-for-road-bikes...