Most accessibility problems happen because the better choice is too hard to make at the moment people need to make it.
When a designer moves fast and doesn't know which pattern to use, they'll use the one that's handy. When an engineer builds from a ticket that says "modal" but mentions nothing about focus, keyboard behaviour or screen reader output, they won't give it a second thought. QA finds all these problem too late, when changing anything means rework. Rework is work everyone thought was done.
Then they say it's accessibility slowing down delivery.
Accessibility is just the trigger.
If we want teams to make better accessibility decisions, our job is to shape the work so those decisions are more likely. That's not by giving everyone a 47-page checklist and hoping they remember to use it under pressure. And it's definitely not by turning one person into the accessibility champion of the whole company.
We have a much better chance by making the right choice easier and having it available as the default choice during work.
What does that mean?
Different roles need different things. It might mean designers have access to agreed accessible patterns for common components. It might mean having accessibility acceptance criteria to user stories. It might mean engineers checking focus order before calling it done. It might mean giving teams a shared answer to "what does done mean?"
This is where product leaders have more influence than they think.
You don't need to review every screen. Teams need to work in conditions where better choices are obvious, expected and supported.
People usually choose what the system around them makes easy. And if accessibility depends on someone remembering to care, it will always be forgotten.