Two different things wearing the same label
"AI website builder" usually means a tool that generates a site from a prompt. You describe a business, it produces pages. The output is fast and cheap and it is genuinely fine for some purposes — a placeholder, a personal page, something to test an idea with.
"AI-native development" means experienced developers using AI to move faster through work they could do without it. Same standards, same review, same architecture decisions, considerably less time spent on the mechanical parts. The output is a normal codebase that a normal developer can read.
These get marketed as if they were the same product. They produce very different things, and the difference does not show up on launch day.
Where generated sites come apart
Generated sites tend to look right and be structurally arbitrary. Heading levels that make no sense, markup that describes appearance rather than meaning, duplicate patterns solving the same problem three ways, accessibility handled inconsistently, and structured data either absent or describing something the page does not actually contain.
None of that is visible to you. It is visible to search engines, to screen readers, and to the next developer who has to change something. The bill arrives later, usually as "we should probably just rebuild it."
What the human is actually for
Deciding what the site needs to do and what belongs on each page. Choosing the architecture and the data model. Judging whether the generated code is correct rather than merely plausible — which is the part AI is worst at flagging about itself. Testing against the ways real customers behave, including the failures. Owning the result when something breaks at an awkward moment.
AI is very good at the parts in between: scaffolding components, writing boilerplate, converting a design into markup, handling repetitive changes across a codebase. That is a large share of the hours in a typical build, which is why the timelines compress.
How to tell which one you are buying
Ask three questions. Can I see the code, and does it live in a repository I own. Who reviewed it, and what were they looking for. What happens when I need something changed in a year.
A generated site usually cannot answer the first two, because there was no review and the code lives inside the tool. Ask them anyway — the answers separate a build you own from an output you rent, and the price difference between them is usually smaller than it looks over three years.