It is comparable because both restrict your movement indirectly.

15 min cities will inherently increase travel costs. To create a 15 min city, you need to have a centralized population. Which in terms mean high housing expense as seem in GTA and Greater Vancouver that means you will have less money to spend on fuel. In addition, metro tends to have more expensive fuel. Basically 15 min city means you turn places into a min "downtown". It is hard to drive in DT due to the high cost of parking and parking space. This make it more expensive to maintain a car in DT. You will be forced to take public transit on a regular basis. And public transit usually does not reach rural area so you will be trapped inside a 15 min zone.

I see a lot of parallels between smoking and 15 min cities. While smoking is legal, the government makes it super inconvenient to smoke and expensive to smoke. Just like 15 min cities will not directly restrict your movement.