Guess I'll idle my car to offset this.  

 This scheme doesn't scale. 

If every TX used paypal's approach, the 'green miners' would end up with thousands of dust UTXOs which they would need to clean up, every single block. Network throughput would drop significantly.

With standard bitcoin fee subsidy, all miner fees are automatically consolidated in the coinbase transaction: No dust to clean up.

Not to mention the fact that this approach doesn't necessarily require the miners to use green energy to mine the TX - it just incentivizes a particular arbitrary set of miners to mine the TX. Those miners could pay off a different non-green miner to mine the TX, because it is still consensus-valid.

Paypal's idea is just a roundabout way of reinventing the same open fee market which already exists, but with a lame attempt at green-washing.