That might be true if you focus on honeybees; but e.g. bumblebees only have 20 to 200 animals per colony and are also the much better pollinators than honey bee

That might be true if you focus on honeybees; but e.g. bumblebees only have 20 to 200 animals per colony and are also the much better pollinators than honey bees; bumblebees also work in bad weather and collect on more plant types (many agricultural plants such as tomatoes are pollinated only by bumblebees); and honeybees - unlike bumblebees - usually have someone to take care of them and pour sugar water when they don't have enough to eat. So you may very well make a difference if the bumblebees find useful flowers in your garden at a time when everything else is mowed down. The referenced site is in German, but it has also some English documents and tables, such as e.g. http://hummelgarten.ch/wp-content/uploads/2018/11/Anleitung-Hummelparadies-EN.pdf http://hummelgarten.ch/wp-content/uploads/2018/11/Anleitung-....