I doubt there is enough demand for them to invest the hundreds of millions per aircraft to provide this service. In addition, each of the routes they would be a

I doubt there is enough demand for them to invest the hundreds of millions per aircraft to provide this service. In addition, each of the routes they would be able to provide would remove gates for other, more profitable flights. Another factor would be turnaround, i.e. cleaning and resetting a ‘pet-friendly’ flight would probably take longer then a regular flight, increasing the at-gate time and thus reducing the number of flights that could use that gate.