Here are few things they could do:
* ensure that where they sell gift cards there are store limits on how many gift cards can be bought.
* track the usage of the card to make it more difficult for criminals to use them.
* put a day delay on the card or make the user register to make it more difficult for the user to immediately sell the card off to criminals
Google is very aware that their gift cards are used in massive fraud schemes of millions of dollars that target the most vulnerable (the elderly). It is similar how there is a huge fraud scheme build on Nest products. That they allow it to happen (as it is of no cost to them) is incredibly irresponsible and in opinion even criminal.
When I called Google, their response was that on the back on the cards there is warning in small print that if you give the scratch off key, the money is unrecoverable. As if someone being told that their entire life will come down crashing around them if they don't send the money is going to read the small print on a gift card!
Google is probably the company in the world that is the best at tracking users and cyber security. There is no reason why they couldn't prevent these use cases if they put effort in.