However if it is some kind of bus or something then no, the kids will not need seats. Many hotels offer bus services, or there may be other airport shuttles, or whatever. So, it might be easiest for you to look into shuttles - then you can even contact the company to make extra sure that you won't need a seat.
Or, you could take your car seats with you. The airline should not count them towards your baggage allowance. It may seem like a PITA to do this but then at least you've got them when you get there, should they be needed for any reason.