Don't understand the question. There is no law saying there has to be bike lanes or bike paths.
No. Bike lanes are are BICYCLE lanes. Meaning human-powered, pedal-driven bicycles. Motorcycles are legally obliged to use the same lanes as cars
No. You'll notice that the bike lane is marked with a solid white line. Anywhere you see a solid white line (such as lanes close to stoplights or bike lanes) you are not supposed to use those as merge lanes.
If the Engine is 50cc or larger it is Illegal to ride in a bike lane
No, but it is frowned upon. Some cities have bike lanes to stop people from riding on sidewalks.
Most cities have some bike lanes, somewhere.
Absolutely not. The reason the bike lanes exist is exclusively for bikes.
They don't care, car drivers are largely ignorant about bikes.
I'm assuming you mean "bike lane" ....And the answer is no, bike lanes are mainly intended for unmotorized vehicles. Scooters and mopeds with small engines might be OK, but a dirt bike is way too powerful.
Unless they're planned in from the beginning, they steal space from the other lanes, making them narrower. And it's also common that they'll start and stop in strange places, leving riders stranded in mid-traffic. A badly planned bike lane is often worse than no bike lane at all.