Please remember, we do not make the rules, we only pay the fines if we break them. In short, what comes with motors are electric matches, and these are exempt. (The file attached is directly from our ATF agent). you can also look here, just search igniters
https://www.atf.gov/explosives/docs...ves-laws-and-regulations-atf-p-54007/download. So what you are getting from ebay/amazon are igniters, and a license is required. Igniters became regulated after the safety explosives act in 2003. These igniters from ebay/amazon also do not ship as 1.4s explosives, which is what the DOT requires (for land and sea), or IATA(air transport)
What we did was develop an igniter, that would not be regulated, this is the firewire. Why the ATF regulated and why they do not, took us 2 years to figure out. However, we did accomplish it, so we made a full line of rocket igniters and starters to legally fill the need of the industry. hopefully this clears up some confusion.