Allowing states, cities and other local governments to require online sellers to collect sales taxes will hurt small online sellers. Example, a self-publishing author (a single person) who sells his/her books directly to consumers through their own website doesn't have the resources to track and collect sales taxes for every possible jurisdiction.
Instead there should be a single flat rate online sales tax at the federal level which after being paid by the sellers is then evenly distributed to the state governments.
At the very least for those online sellers that consist of a single person who sells only their own original products, such as an author selling his own books directly to consumers.