[contravariant]

The amount of effort required for 10 million trees a day would require everyone in the US to plant a tree each month. This would likely also require people to care for enough saplings to plant a new tree each month.

It's not an insurmountable level of effort per person, but if you try to do it on a large scale you inevitably end up with logistical problems, and it would require quite a lot of space.

[logical_proof]

I am not sure I understand your math here. Let’s say every adult in the US, 300M, plants a tree each month for 12 months, 3.6B trees planted in a year. Or are you factoring in saplings that fail to grow or something? Is it that bad that for every 160 trees planted only one survives?

Edit: strike that I see what you meant there with the a day. I just should have actually read what you wrote before I commented.

[pySSK]

US adult population is around 200 million.

Also, they can't even get people to wear a mask or take a shot. Getting all these people to plant trees seems like an insurmountable task.