Exactly, burdening a business in Kansas to collect taxes for California (especially when every County in California has a different rate) is ludicrous and would require Federal Enforcement.
What these States are not admitting is that the sales tax alone would not be much different than the shipping costs. The reason online retailers frequently have much lower prices to begin with is all the beatings that brick and mortar stores take in States like California from Government regulations, these costs are reflected in everything they sell before the sales tax is ever levied.
The State governments do not want to back off the oppression they are causing that would actually allow their in-state stores to compete because they think they can get the sales tax from online retailers and keep all the local crap in place.
The “competition” claim is just a ruse.
Amazon is now collecting sales tax for California from online retailers located out of State, the delivered prices are still 15 to 20 percent lower for like items purchased out of State even with the tax added. No local retailers will benefit from this change but the State will get to keep raping businesses in their own State while also collecting the sales tax from other States.
The only way that Market forces can do their job of FORCING the States to compete with each other in regards to the business climate they structure is to let technology like the Internet expose their Confiscatory and Authoritarian philosophy for the failed model that it is.