I have a closet in the basement where when I did the vinyl plank floor, I ran out so the planks don't quite go to the back of the closet all the way. Problem? Yes? A bit ugly? Yes. But in reality the problem is 100% of the time covered by boxes and anyway I can live a happy life in this house for decades and not be affected. That's 0% tech debt.
On the other hand if my gutters are clogged, there's interest on that because the longer I wait the costlier it will be to deal with since clogged gutters can lead to basement leaks or gutters themselves detaching. Or, if my stoop is broken, that's not just an eye sore but I keep tripping on it, the faster I fix it the sooner I stop tripping. That's a high-interest debt that should be fixed asap.
In engineering, a high-rate debt could be some architectural thing that slows down the development of every single feature. You want to quickly pause features to pay this down so everything can move faster. On the other hand, some file that you never touch having some shitty code or lots of TODOs may be a very low interest debt since in practice you never touch it or are otherwise not bothered by it other than knowing that it's ugly - like my closet floor.
Engineers make two mistakes around this - fixing zero-interest debt when there's more important things to do on one hand. On the other hand, when they say "oh, product management/leadership didn't sponsor our tech debt fixing" - it's often because we fail to articulate the real cost of that problem - explaining that it's high rate and how it's costing you.
Nobody gets in shit for telling their developers to code faster.
Lots of risk telling them to fix the underlying issues so they can ship faster in the future.
Maybe it is like those restaurants with dirty bathrooms. Most customers don't care, and if you get some minimum customers management thinks a bathroom makeover won't matter.
You're making it sound like having someone quit is a blocker. Some managers see that as shedding the dead weight, and keeping in the guys who are the team players with endurance. The guy who complains about code quality suddenly leaves and all of a sudden there are no more complains about code quality, and worst case scenario you have new joiners trying to onboard and cause a good impression who don't care if code is shit because their goal is to shine.
How did you solved that problem?
If it's one of the few business that has an absolute monopoly over a certain sector in a country, then the country will gradually weaken over time, until eventually it won't be able to resist a foreign competitor.
Or at least that's what market theory suggests. Of course the period of 'self-correction' could take a few months to a few centuries to fully play out, and simultaneously overlaps with all other market participants.