Can dogs be brought into the car? Yes, but you must comply with local laws and regulations and ensure the safety of your dog.
Dogs are not allowed on buses. Except for special-purpose dogs, most other animals and plants are not allowed according to regulations. For details, please refer to laws and regulations such as bus riding rules.
If you take your pet on a bus or other public transportation, it is disrespectful to others. The driver and crew can refuse to take the pet. Pets are not allowed in most public places. In theory, there are regulations not allowing pets on buses.
Buses are public spaces. Pets are not people after all. If the owner does not control them well, the dog may hurt other people. Moreover, dogs have a smell, which may be objectionable to some people. There may be certain germs lurking in your dog, and you may be immune to them, but if you have children or the elderly who are not immune, they may get sick if they are exposed to them. Or it would be bad if the dog gets into the car and becomes unstable and keeps barking, causing a commotion.