First, no it's not just SSE, you are correct, but they were the first to give the links to the proper place where one could obtain a permit.And that b/c there are many SSE members from many countries
This all started many years ago when the Gov did place a ban on importation of seeds to the US, and it was to prevent so called noxious weeds from entering,as tumbleweed did.I think I posted about this before.
And yes customs did flag some stuff coming in and yes,they also confiscated the seeds. Same as what happens if you try to send seeds to Australia, but that's trying to prevent spread of the potato spindle viroid which also infects tomatoes and has now been found in a few places in the US. Same as the ban on getting stuff into the Netherlands,especially tomato seed b/c there are so many companies there that breed varieties and send they send them everywhere for commercial sale.
What it has come down to is large commercial shipments coming mainly from Europe to the US do have to have a phyto, but they have labs that test the seeds before they can be released.
At other forums where I have posted in the past there were several who did have their seeds confiscated.
That's the way I see it now.
Carolyn