Arguably carnivores have already cut meat intake, at least red meat, to greater impact than vegetarians.

While I’m going by anecdote rather than data

• vegetarians/vegans are a small minority so limited impact
• many people I know have cut back on at least red meat for health or environmental reasons.

Basically one fewer burger a week by 100 people has more impact than one person not eating meat at all

Punishment doesn’t prevent behavior that already happened and is usually missed. Road modifications help every time.

My town has a major road that was one of the most infuriating and dangerous in town. It was two lanes in each direction, constant jockeying for position or to make the light or to get around a turning car.

All it took was repainting. Now it’s one lane in each direction with turning lanes. There is no jockeying for position since it’s only one lane. But turning cars are no longer blocking so no infuriating stop and go. They even coordinated the lights.

Now that road is slower, calmer, no road rage or angry drivers and everyone gets through in less time

Just look at how much less food and other aid the US is giving out. Clearly the problem is solved