I think most engineers are just not used to ever thinking about time and money as a constraint - they're just things abstracted away from them so they can do good work (or they've worked for companies where those aren't constraints). Just being up front with them about the fact that these constraints exist will usually change how they think about a problem (in my experience at least).
> The problem is if the tech debt is not a conscious decision you're making
100%. The entire debt metaphor fails if you aren't knowingly doing something that you're going to have to "pay off" later.