I just want to know what are the possible issues. I had to raise an issue for non-unique IDs, but the rest of the team didn't consider it to be very important.
In some ways, I'd agree that it would be a low priority bug.
Since the devs here are essentially using IDs like Classes, then the issues I see are:
Browser JS console may contain extraneous warnings or errors (noise), which could make it harder to diagnose bugs when they occur.
Same with log files. It could create extra noise.
HTML won't pass linting or HTML validation tools.
If there's test automation code that uses those incorrect IDs, well, the problem there is doing a
.FindsByID will only find the first one as it expects only one. This would also be an issue with Xpath locators or other more complex CSS locators.
Ultimately, in order to get this fixed, I think the devs need training on proper use of IDs vs Class. And, you'd have to speak to them in language they'd understand, as in, how does this current way affect them? Right now, it seems they don't want to fix it because it creates too much work for them.