It really is explained really poorly, as is all haki in general but especially this.
Luffy seems to be infusing his CoA barrier/ID with CoC so no touch while Kaido is just infusing his club so touch but then why is 2 AdCoC clashing always no touch?
Luffy seems to be infusing his CoA barrier/ID with CoC so no touch while Kaido is just infusing his club so touch but then why is 2 AdCoC clashing always no touch?
But if you think about it, if one person is using a barrier and the other is clashing with that barrier the clash will be non contact by default. So it's not necessarily proof Kaidou is using one.
I don't feel like checking but I don't remember a non contact clash Kaidou had with Yamato. If you could bring one to the table it'll change some things but there's also something else we can factor in:
Barrier haki (by default) =/= internal penetration. Oda has to give us a marker for when both are being used in conjunction with CoC and I believe it is that effect he uses when Big Mom punched Page 1, and Luffy is punching Kaidou. Kaidou has never been drawn with that effect even once.