SHHHHH!
Are ye trying tae wreck ta Scottish tartan industry? Don't gae aroun letting oon thet thar ware nae "Tartan Police" in ta Highlands 300 years uhgo, and tha' women spun and wove tartans tae whutevuh patturn they pleased, and did nae jes mindlessly reproduce soom patturn laid down by uh clan chief? Do ye knoo how many wee bairns will wind oop starving, with thar pare parents on ta dole, iffen ye let Uhmereicans knoo that ta custum of distinct tartans fer everuh clan was envented by Victorian mill owners tae increese thar sales?
/Willie the Groundskeeper voice
But I couldn't understand far more than half of the people I spoke with.
Groundskeeper Willie speaks perfect english compared to the real Scots.
The Great Tartan Nonsense is highly amusing, and as you say it keeps the wee bairns in haggis . . . .
There IS a demonstrable pre-1745 connection with districts, rather than with particular clans, simply because local weavers had favorite patterns. So you often have a general association between the clan that is most populous in a district and the weavers' pet patterns in that district. From that you can have sort of a clan association, but it's pretty tenous.
I wear whatever tartan I like -- my dad's a MacGregor, my mom's a Glencoe MacDonald, but I think the MacGregor tartan's a little too garish for day wear so I wear the blue Hunting MacRae, just because I like the pattern. My husband's "official" tartan, Mar, is not only hideous (purple, magenta, and orange) but also only woven to order, so he wears Gordon. The mill owners still make plenty of money off us (although the better known setts are cheaper!)
Here's a Tartan Finder should you be so inclined . . .
Polish mill owners at that.