You are all missing the point. Many of us have stand-alone business that have absolutely nothing to do with Amazon, eBay, etsy, and all. We sell directly. We now are facing taxes to about 10,000 jurisdictions. Sure, maybe some state filings will work but how will we know? If I sell to someone in NYC, they want tax, the state wants tax, and, if I recall correctly, they want my company to register as a foreign corporation. Other states, like Texas, require similar to sell to customers in their state VIA THE INTERNET. Been easy to ignore but now that we are risking tax issues, this becomes a lot more serious.
Only the state wants the tax. The other juirisdictions get the money from the state. They do not get it from you. You have to file in 50 states and I am by no means trivializing that. It will be time consuming or you will have to give up a chunk of profit for some service.
As you collect tax for those 10,000 (actually 7,000) jurisdictions, there are services that will tell you how much to collect. Those services cost about 10 cents per transaction. There is no effort involved, just that fee. Then, like I said, you have to file in 50 states, probably quarterly depending on amounts which will be time consuming unless you pay for a service to file for you.