The whole concept of decentralized trust-less environments requires some way to prevent malicious attackers from taking over the network. Proof of work, while extremely wasteful, does that job.
The main problem is that trust-lessness and decentralization isn't actually necessary, especially for most things that exist in the real world and are at the mercy of the legal systems they operate within (this applies to cryptocurrencies as well - the government doesn't need to break crypto, it can just make interacting/transacting with it illegal).
For a lot of real-world projects, the legal system is an adequate protection. Centralization doesn't require a profit motive - the central party could be set up as a non-profit and then have all the advantages of a centralized system while avoiding a lot of the drawbacks we see in for-profit operations.
> Proof of work, while extremely wasteful, does the job.
True, yet you could even have Proof of Work without cryptocurrency. Cryptocurrency is used to incentivize PoW which attracts more people to the blockchain and strengthens the network and so on.
However, one could have Proof of Work without cryptocurrency, for example, one could reward the PoW with participation in the blockchain, or in this case, have drivers PoW to be able to take rides.
> Centralization doesn't require a profit motive
Yes, I also agree that centralization doesn't require a profit motive, and a centralized solution is deal for 99% of the cases.
The main problem is that trust-lessness and decentralization isn't actually necessary, especially for most things that exist in the real world and are at the mercy of the legal systems they operate within (this applies to cryptocurrencies as well - the government doesn't need to break crypto, it can just make interacting/transacting with it illegal).
For a lot of real-world projects, the legal system is an adequate protection. Centralization doesn't require a profit motive - the central party could be set up as a non-profit and then have all the advantages of a centralized system while avoiding a lot of the drawbacks we see in for-profit operations.