Yes, they are and they also know it isn't foolproof so that isn't the only information being compared against. Some services compare the calling number is compared against live activity on the PSTN (ie, subscriber's phone is not in an active call, but their number is being presented as as the caller ID is one such metric). Many of these deep fake generators with public access have watermarks in the audio. The audio stream comparison continues, it needs to speak like you, word and phrase choices. There are other fingerprints of generated audio that you can't hear, but are still obvious at the moment. With security, it always cat and mouse with fraudsters on one hand and the effort/frustration with customers on the other.

Asking customers questions that they don't remember and that fraudsters have in front of them isn't working and the time it takes for agents to authenticate is very expensive.

While there is no doubt that companies will screw up with security, you are making wild accusations without reference to any evidence.