That's a rebranded tube, Chip. Meaning that it was manufactured in an actual tube factory and sold in lots to other NON-tube-manufacturers and relabelled as their own. Many times you can still see the original faded, partially rubbed off printing on the tube as well as the new printing. Take one of those suckers out and examaine it closely; hold it up to the light and see if you can still see the original printing. I have some vintage 1962-63 Wurlitzer 12ax7 tubes lying about that are even labelled as "Made for Wurlitzer by G.E."
So yes, they are Wurlitzer tubes. No, Wurlitzer did not make them.
https://en.wikipedia.org/wiki/12AX7
"As of 2012 the 12AX7 was made in various versions by two factories in Russia (Winged C, formerly Svetlana, and New Sensor, which produces tubes under the Sovtek, Electro-Harmonix, Svetlana, Tung-Sol, and other brands for which the firm has acquired trademark rights), one in China (Shuguang), and one in Slovakia (JJ Electronic)....."
The one major U.S. tube manufacturer (RCA/General Electric) shut down in 1986 and likely stopped producing the tubes themselves as early as 1976-78.
Mullard had a handful of factories in Europe, and "Philips continued to use the brand name 'Mullard' in the UK until 1988. Mullard Research Laboratories in Redhill, Surrey then became Philips Research Laboratories. As of 2007, the Mullard brand has been revived by Sovtek, producing a variant of the ECC83 and EL34..." https://en.wikipedia.org/wiki/Mullard
Again, no tubes were actually manufactured by Groove Tubes, Mesa, Fender, Wurlitzer, or even Jackson. Feel free to contact any of these companies to inquire where they "make" their tubes.
Maybe ask for a tour of such factories as well?
Why rebrand things? There's plenty of reasons, mostly due to availability and supply (or lack of), overall costs, warranties, etc.
I can tell you this: about 12 years ago I worked in a factory that made wiring harnesses for several various big-name manufacturers. Besides the wiring harnesses that we made in-house, every week or so a truck also showed up and dropped off about a hundred boxes of wiring harnesses from some other factory in China. These boxes were unpacked, sorted, and all "Made in China" stickers and designations were removed. These very same wires were then reaffixed with "Made in USA" stickers and labels, reboxed and
shipped out as our own. WTF!!! I did not ask anyone in charge why this was happeneing, and the ladies doing the actual work didn't seem bothered by it either.
Just a paycheck.