[tsimionescu]

The protocol is not immutable, and there have been several changes to it in the early days, and several proposed changes that keep being discussed (such as the famous block size limit change). If the people developing the software and the major mining groups agree on a change, who will stop them?

[CryptoPunk]

It is extremely hard to organize a protocol change that succeeds in tampering with existing smart contacts, let alone eliminates the permissionless/neutrality guarantees of a public blockchain with significant adoption.

For a public blockchain with as large a userbase as Ethereum, a protocol change that nullifies its neutrality and permissionless-ness would be nearly impossible for any group to push through.

It's absolutely incomparable to traditional banks, with respect to the degree of resistance to interference from governments.