It seems (to me at least) that is is generally accepted that "electronic identity" and "digital signatures" are a different thing. For example, in the Estonian ID card there are two certificates - one for identity, and one for signing.
They correspond to the real-world actions of "showing" your ID card to the authorities, and signing a document, respectively.
However, I don't understand why they have to be different. The same technology with the same infrastructure is/can be used for both. Why can't you use your digital signature for identifying yourself (or your e-identity key-pair to digitally sign a document).
In both cases you use your private key to sign something.
There are implications, of course, e.g. you may think someone is just verifying your identity, but in fact you may be signing a document that you don't want to sign. But one can offer you to sign a harmless document (e.g. "please sign this digital receipt" nonsense), but in fact you may be signing for a loan. People can be tricked via the user interface for digitally signing/identifying either way. (Related question: what are the ways to prevent that from happening?)
Is the distinction needed solely for protecting the owner, or there is a bigger factor for splitting a single technology solution into two?