It's due to different consensus mechanisms.

Bitcoin and Ethereum in its current implementation uses Proof of Work, which is a very energy intensive process, and the energy used helps protect the network by ensuring its very costly for bad actors to attack the network.

For newer blockchains like Cosmos, which uses Proof of Stake and Solana which uses Proof of History, they have other mechanisms to protect from a 51% attack, and so does not need the validator/miners to consume energy like the Proof of Work consensus systems.

Solana is pretty centralized, it was designed to be an efficient version of a blockchain. So, it works more like a traditionally engineered HA service would, but with some blockchain bits attached. This makes it fast and cheap, but it isn’t very decentralized as a result.