99% true with some very few exceptions. I remember Evan Davis' on a BBC podcast called "The Bottom Line". In said podcast he was interviewing various business people.
One of them was the CEO of Primark.
Over 'here' (in Europe - in multiple countries) you can see MASSIVE stores (I haven't yet been on a Primark store that was smaller than a football pit (per floor - typically two floors - lower for women, upper for men and kids), and they have shockingly low prices. I haven't visited a Primark outside Europe yet, so I have no opinion about other regions.
So.. back to the CEO.. he was responding that their low prices is not because of low quality, but because they never spend a dime on marketing, and thus they can use these savings to improve quality and lower prices, and then went on to challenge the journalist to remember/find one (paid) advertisement.
At that point (5? 6? 7? years ago) I also tried and for the life of me I could not remember ever seeing ads on the Tube (London underground), newspapers, bus stops, internet (but I block 99.9% of them).. anywhere.
So yes, 99% true but then I have a black long-sleeve t-shirt Cedarwood (Primark product) that 5 years on is still in great shape and I do wear it a lot, while the respective H&M don't go past the 2 year mark.
If you look online, Primark continues to engage in this illegal behavior after getting caught on numerous occasions, just like Walmart.
https://www.business-humanrights.org/en/latest-news/minimum-....
https://www.theguardian.com/global-development/2021/jul/02/w...