Not sure ridesharing is the best fit for decentralized solutions. A big role of these companies is performing background checks and dispute resolution, and those seem hard to do in a trustless decentralized system without exposing loopholes that can be exploited.
there are a lot of people that need rides.
There was a company that facilitated these two meeting and took a cut of payments.
It does not need to be a company. It can be an autonomous entity, eg a smart contract. Think ethereum + ipfs. just by way of example.
in other words, cut out the middle-man. Remove the target for governments to pressure and tax.
At that point, the free market decides.