This maybe works well when there's only one bicyclist, but what if there's a whole group, with half of them using these laser projectors? There would be a huge green mess on the road, not very practical.
Besides that, governments will never allow random citizens to make their own street marks. It interferes with traffic regulations and laws.
I feel like you've misunderstood the aim here. It's not /really/ to create a new cycle lane, it's to provide a visual indicator of the presence of a bike in a place where a motorist who has a cyclist in their blind spot will see...
Lots of them will provide a very noticeable indicator, and that's good.
Exactly. It's not intended to be a "street mark" but an attention-getter. Bright green mess on the road? Where's that coming from? Yikes! A flock of bikes! (I did not intend to rhyme ... :-/ )
Besides that, governments will never allow random citizens to make their own street marks. It interferes with traffic regulations and laws.