Engineers can't solve #a11y problems that are rooted in faulty business or design decisions. They can _make compliant code_ to cover over those decisions. But it won't result in fundamentally better software if it's not conceived with inclusion in mind.
Beware the engineering manager who asks business/design questions (e.g., "how many users are we talking about here?").
Why? THAT IS NOT THEIR JOB. They are likely just giving you their excuse in advance for deprioritizing the work.
If that's what's going on, you have a product management problem. Pushing back on eng without PM/mgmt being involved won't get the change you want.