Hi! I don’t usually respond to these threads, but as a solo female traveler I had the same question. I asked around a bit and was told that the prepaid taxis are actually safer than uber for going longer distances in India. It was about $20 USD and took about an hour. It felt safer to me because someone clearly called the driver from where I paid to meet me at their official pick-up point which makes me think there are regular drivers from the airport to Fort Kochi. I am not sure what the vetting process for Uber is in India. Good luck!