Also allegedly a reason for female radio operators in WWII, though it might have been anxious staff procurement wanting to avoid having female appointments blocked.
However I don't think it's a frequency response issue, but the idea that fainter female voice with more background noise is easier to understand. So I suspect that the software is poor rather than anything inherent about female voices, which can be clearer (certain parts of Brooklyn, Dublin, Yorkshire and West Country may be exceptions).
I expect they have poor choice of samples, despite claims that it's some other problem.
The only difference I see from 25 years ago is that it seems to skip the personalised user training and give about the same performance, poor. The phone menus with voice recognition are ghastly compared to numbered menus, which are ghastly. None of it is to make a better customer experience but to save money.
Same with evil automated checkouts, which encourage some people to cheat. No doubt the thefts are less than cost of a checkout operator. I don't expect transparent & honest figures for how accurate Amazon's invisible checkout is. Next step is to ban customers from aisles and have Argos style terminal (identical to online website / phone app) and you queue to wait for shopping basket to appear. Pay by paypal, IBAN, plastic or RFID phone.