I'm 100% on board with not mixing them and making sure everyone on the team is on the same page. But that's a red herring; it can easily be remedied with linters/editor settings. The same is true for preventing tabs.
My editor (VSCode) notifies me if I open a file that has any mixed tabs and spaces and offers to fix them all with one click.
> no way in hell am I going to change Vim to display them differently!
Sounds like we've found the problem.