Car seats.

What are your stands/views on carseat if u do not own a car? Won’t be be extra unnecessary costs n thing to bring out? I get that it’s for safety but how do u lug a car seat around if u don’t own a car n u’re just taking taxi? Personally I don’t own a car n also don’t have carseat, I usually travel via public transport because I feel it’s more convenient but when I do take a cab I just carry my 16mo(been doing that since she was a newborn) n was just wondering how u guys lug an extra car seat around