I'm curious because I do see kitchen knives for sale on eBid. I do have some chef's knives and steak knife sets I would like to list. I can understand the ban on weapons-type knives, considering the restrictive laws.
In the US sales are generally restricted to those over 18. There are also a lot of restrictions on "assisted-opening" knives, which is a nicer word for a switchblade. Years ago, that other auction site allowed assisted-opening knives with blades of 2 inches or less. Let me tell you, there were hundreds of 4 1/2 inch blades listed as 2 inch.
I sold a large collection of vintage pocket knives and some newer Case models on the other site. I agree it would be nice if Case was available, but it would be hard to draw the line between "collectible" and "weapon" knives.