It's more about what the company considers core business and what not. Most often they don't see the website as being important enough to the business so they don't invest in it.

We have gotten used to almost flawless experiences from amazon shopping. Google search finds (or used to) results sometimes almost like magic, etc. The thing is, that's the core business. These companies invent new technologies and have huge teams because doing this is so hard.

Now take a random supermarket chain. Their knowledge is about physical stores. Their core business has taught them where to open a store and how to arrange things in it so that they maximize their sales in that environment. It's very hard and it takes a very long time to shift to an online model. You have to find people with the right competencies and the right leadership to convince the company to do this and this is actually very hard to do.

Look at the categories example. That, to me, screams backend database. The company has invested a lot of money into building business intelligence on top of their physical stores. That organization screams "perfectly curated data warehouse" and I imagine suggesting something like "we need to reorganize the way we store data" is going to be met with blank stares if not full on outrage.