We took our little girl to Spain and took our egg car seat but she was only 6 months. We got given this advice from the health visitor as their car seats don’t meet UK regulations she said. I’m glad we did though because it meant she slept in it on the way to and from the airport. We also had to rent a car for a day and she slept on those journeys too. The car seat came back on the plane fine too both times! The only pain is you have to carry it to the plane door, she we had the pram and the car seat x
How old is baby? Under 1 year we did but its a bit of a pain! You wouldn't use a car seat on public transport and you don't legally need them in taxis but obviously you'd be safer using one. After our eldest turned 1 we contacted taxi companies beforehand to request a car seat for long journeys. Depends on the country. In short taxi rides which aren't prebooked we would hold him and ask the driver to drive slowly