It says the "may" deduct, not they "will" deduct, which could allow wiggle room for special situations.
https://support.google.com/googleplay/answer/2453532?hl=en
Now in the Warranty section they say if it is defective you "may" be entitled to a refund, replacement, or repair.
https://support.google.com/googleplay/troubleshooter/3070579?rd=1
Not sure "who" determines which of those options to take.
I guess if they really want to be stubborn, you can wear them out on the replacements which everyone knows will not address the issue unless they include a software fix from Google. Eventually they'll cave and either refund your money or they'll be a fix out by then.
So the key may be that you need to initiate the return via a support ticket rather than as a normal changed my mind return.