Because you can hang up if you aren't. Additionally, I imagine upon reaching an individual immediately stating you do not consent to being recorded will likely trigger the appropriate outcome.

Depends on the seriousness of the call.

If you're entering into an actual contract verbally (e.g. applying for insurance or a mortgage over the phone), they'll typically go out of their way to ask if you're okay with the recording. They don't want even the slightest admissablility issue, and they want you to know you're giving a binding verbal signature.

If you're just talking to a low-level customer support rep, the stakes are a lot lower.

If you not okay then you simply hang up, no?