Produced 'under license' basically meaning that the named manufacturer takes responsibility for the end product and in theory has inspected the facility and are in charge of quality control.
Done properly, think of BMW or Triumph producing their bikes in Thailand or Asia. They don't own the factories (I know both do now but they didn't before) but they make sure the final product meets their quality standards to uphold their brand whilst benefiting from cheaper production costs. That's not suggesting these countries produce poor quality products at all, most are highly skilled competent workers.
Unfortunately, not everyone has such high standards and companies quite often use generic factories to produce their goods 'under license' but in fact have very little control or interest over quality control after their initial inspection run.
The same factory could be producing tyres or products for a number of different brands under similar arrangement's, and quite often on short contracts to only produce one or two runs.
Think of it a bit like sub-contracting.
Say for example, Kawasaki produce a new Z1000SX and throughout testing they have been using a few different tyres but decided to go with Bridgestone S22's. They enjoy a nice relationship with the manufacturer already and have probably been provided with a nice healthy supply of new S22's for testing. This benefits both Kawasaki and Bridgestone, as Bridgestone will effectively get some free product testing.
They sign a contract with Bridgestone to supply the tyres for all new Z1000SX's. As a part of that contract, Kawasaki need an initial run of 5,000 units to fulfill their initial projected worldwide sales (an estimated number). Bridgestone will have agreed a certain time frame of which to deliver those units to fulfill their part of the contract, or risk financial penalties.
Bridgestone won't want to interrupt their current production line, producing high quality products for individual worldwide orders, that's their bread and butter after all.
Therefore Bridgestone turn to one of their already 'pre-approved partners' which could be based anywhere in the world, and contract them to produce the 5,000 unit order for Kawasaki.
Bridgestone will want to keep costs down as the price for the tyres will already have been agreed with Kawasaki as part of the contract, and at no doubt heavily discounted against what they would normally charge, so they can outbid the competition and maintain their relationship with Kawasaki.
Therefore the sub-contracted partner will be under pressure to produce the high volume of units as fast and as cheaply as possible, so they can make money themselves whilst also fulfilling their contracted timetable with Bridgestone. The first few hundred will be inspected by Bridgestone to make sure they are so called on par (but likely slightly less is acceptable) with their own standards and from then on probably only inspect a random few as production continues.
As a result you are left with perfectly adequate tyres, for the most part, but don't compare to the 'in house' produced units over longer periods / harder use. Some are worse than others and some manufacturers worse than others.
Considering new bikes are ridden gently during the run-in period and generally by tentative new owners who don't want to drop their new pride and joy's, consumers don't usually find out until it's time to change and therefore Kawasaki or Bridgestone don't care.
Dealers love to charge you for a new set "fitted with your next service shall we, sir??"
and are encouraged to do so by both Kawasaki and Bridgestone as they all know that's when you're most likely confident enough to start 'pushing on' or 'making progress' as those of you AdQual members will say
The first service for most owners won't occur until after a year of riding (the average annual mileage for UK bikers is less than 5k, and that's similar throughout the Western world, sadly) so they probably won't notice the difference much.
It's only those of us hardened all year bigger mileage bikers who will mutter a complaint or two, but usually not loud enough to make a fuss
Also as MDR stated, an added letter 'n' or slight design difference will probably cover the legal bit. But it would also help the manufacturer differentiate between which ones we're produced where.