Short answer: the bank won’t give your shiny new tree-planting business a loan as easily as it will to a “liquid tank tree replacement” one.
Long answer:
- Trees take time to grow
- Trees need to be planted
- Trees make shade
- Animals like birds and insects like bees and mosquitos like to live next to them
- Trees don’t need electricity
- Trees take in heat radiated from the pavement
- Trees don’t look cool
While algae are more efficient at turning CO2 into oxygen in theory, in practice algae don’t have a good climate in such a tank (no oxygen without ventilation, i.e. constant electricity and they get cooked through the glass).
All in all, more of a gimmick than anything.
You could also open a 2nd restaurant if the first does too well - just say you use it to make your great food accessible to more people and to test new products before risking your reputation. The part about “I want me some cash to mix in some of my dirty money” can be strategically left out.