Such simplification might include a single rate per state and a way to do a single filing that covers all states one sold items into.
I.e., something similar to how the EU handles VAT. Here's how we as a US company handle VAT in EU countries. First, we registered with the tax authorities in a single EU country. We are using Ireland. This took something like 20 minutes to figure out and was all online.
Then, once a quarter we upload a file to the that country's tax office that simply lists for each EU country how much we sold, what VAT rate we used, and how much VAT we collected, and we give Ireland all the collected VAT. This only takes a few minutes I believe.
Ireland then deals with sending each of the other EU countries their share of the VAT we collected.
There is an ongoing effort to do something like that in the US with the Streamlined Sales Tax (SST) project. Almost half the states have joined that. The deal there is that if a seller agrees to collect tax for all the SST states then those states will pay the costs for the merchant to use some third party tax service, such as Avalara, for this.
That's nice, but does not include any rate simplification. With simple rates, like in the EU, I don't need to hook my cart up to any external tax APIs. I just need an internal table of the per country rate. I use an external API to keep up to date when a country changes their rate (which isn't very often), but that can be a daily cron job rather than something in the live cart path. With the bazillion rates per state model of the US you have to hook your cart up to a third party tax API.
SST also doesn't help with the states that aren't part of SST. Of course the third party tax services such as Avalara are happy to handle those for you too, but not for free like they do with the SST states.
An EU style system with both simple rates and a being able to deal with all states through one free service is probably too much to hope for. But maybe Congress requiring states to join SST if they want to force out of state sellers to collect would be achievable, and that would be way better than the current mess.
