Because transaction fees on blockchains run as an auction market, low-cost transactions are enabled by high transaction throughput, at least relative to demand. In other words, any chain that has high throughput and/or low demand will have low-cost transactions. Solana and Ethereum attempt to achieve high throughput in very different ways.

Ethereum blobs create transaction space that has a 0-of-n trust model (for zk-roll-ups) or a 1-of-n trust model (for optimistic roll-ups). This means that there needs to be either zero or one honest participant who carefully receives, processes and validates every single roll-up transaction in order for an outsider to be able to prove that the chain was not tampered with.

In contrast, Solana achieves throughput by taking the classic blockchain structure (with its n-of-n trust model) and cranking the parameters up to 11. Basically they said "be a standard blockchain, but do everything a hundred times faster on expensive servers with beefy CPUs and datacenter connections". The advantages are that it took less development time and there are less moving parts in the stack. The disadvantage is that the Solana blockchain is not actually verifiable, in the sense that you or I could download a piece of software onto our home computer and follow along with the chain to make sure it's valid. Ethereum is verifiable in this way, even down through all of its (properly-designed and fully implemented) L2s.

To distill the entire situation: In order to scale, Solana gives up some of the fundamental properties that make blockchains powerful. Ethereum, scaling with blobs, retains these fundamental blockchain properties.