These plates are a passive, very visual reminder. A tracker app requires you actively use the app, and not consciously/subconsciously underestimate portions.
Neither is a holistic solution, both require buy-in, each is going to have different effectiveness for different people.
These are not a good way to track how much you eat, get a calorie & nutrition tracking app
Passive vs active engagement.
These plates are a passive, very visual reminder. A tracker app requires you actively use the app, and not consciously/subconsciously underestimate portions.
Neither is a holistic solution, both require buy-in, each is going to have different effectiveness for different people.
While it’s true that multiple strategies can be helpful, I don’t think the tiny “skinny jeans” circle on that plate is anything but a harmful idea.
Portion sizes are not the same across one meal