Initially, nurseries are the problem in some cases. The flowering white pear will take over North America, one subdivision at a time. Don’t even get me started on that damnable pestilence Bush Honeysuckle (originally sold by nurseries back in the 60s as privacy screens).
I have honeysuckle close to my house at the farm, that was from cutting at my grandmother’s mother’s house.
I have a Lilac bush that is from cuttings from a Lilac bush brought from Virginia to Texas by my Grandmother’s family. We planted it in my daughter’s yard in N. Virginia.
They have labeled as invasive what my grandmother had in her flower bed by her front door, perrywinkle (Vinca). They never were invasive in this part of Texas.
I can think of a lot of plants that are invasive, my family has owned and operated farms in this county since 1889.
I know about invasive weeds.