Last I heard, It's partly a demographic issue. There are not enough people with a need for that kind of heavy protection to justify giving much shelf space to such products. 10-20 years ago, there was an increasing need for such products because the population of aging Greatest and Silent Generationers was growing and with it, the demand for products that were effective for managing heavy incontinence. I still don't think premium brands could be found in stores back then but brands that could be considered pretty close to premium were found in stores. I.E. Attends, Tranquility etc. Some even carried a few generic medical brands and their own house brand, and Depends has always had a presence. Around the mid 2000s the aging population of the era started to die off and with it, the demand for such products that offered heavy and extensive protection. Now? The Baby Boomers are the aging population of the time, however, they are not quite there yet. most Baby Boomers, especially the oldest ones are fine and don't have any incontinence issues and those who do have very very minor leakage issues and don't need the extensive protection of traditional tape on diapers (yet). So since around the mid 2000s, stores have been giving up shelf space in favor pull-up type products as that's where the demand is now. chain Pharmacies like CVS and Walgreen's only carry their house brand and Depend's diapers are nowhere to be found. Depend pads and pull-ups are there, but the only "fitted briefs" as many call them are the store's house brand. Rite Aid carries Depends diapers and their own house brand but products for lighter protection are the stars of the show so to speak. Walmart carries Depends but only in small/medium as well as their house brand, Assurance in all available sizes. Kmart carries Depends. Grocery stores and other retailers like Target such products are nowhere to be found. All the shelf space in those stores is fully dedicated to pull-up type diapers and other products meant for lighter protection.
However, there is one thing working in our favor, people are living longer. The more time goes by, the longer people continue to live. As the oldest of the Baby Boomers begin to age into their 80s and 90s, the demand for heavier protection should increase across the board. This could lead to a population shift where there are just as many old people as there are young people or even where the elderly become the majority. Such a shift has already happened in East Asian countries like Japan and China as in stores, especially in Japan there are products for all forms of protection all the place sometimes with the actual products on display. So it is my prediction that such a shift will happen in the West when the time comes. It's not a matter of if, it's a matter of when. In the coming 1-2 decades as the oldest of the Baby Boomers age into their 80s and 90s the need and demand for tape on diapers could skyrocket once again, just like it did in the 90s-early 2000s. Most premium diapers will still probably be exclusive to e-commerce, but brands like Attends and possibly Tranquility could be seen in chain pharmacies and retail stores once again and possibly a few generic medical brands. More medical supply stores may carry premium diapers like Molicare and Abena. And stores could drastically improve their own house brands to compete for shelf space. imagine what the 2030 edition of Certainty, CVS, Rite Aid, or Assurance diapers will be like.
In short, It's only a matter of time, we're not quite there yet, but we will be in the coming decades.