Although interesting that Google's turnover rate is close to Amazon's, one year turnover is horrible. Other large tech companies (like Microsoft and Apple) have much lower turnover rates.
Tenure is not turn-over. If you double the size of your company every year, but nobody quits, then your average tenure is <1 year. Nobody would be able to accuse you of having high turn-over, though.
On the other hand, if you grow your company by 25% year-over-year, and your entire staff quits after 18 months, your average tenure will be >1 year.
On the other hand, if you grow your company by 25% year-over-year, and your entire staff quits after 18 months, your average tenure will be >1 year.