Who thought it was a good idea to 'mail' live animals? Seems like a rather harsh thing to do... especially when it's done using a process that doesn't care about what it is mailing. (regardless of who is influencing that process)
[0]: https://www.history.com/news/mailing-children-post-office
These include bees, day–old poultry, adult birds, and small, harmless, cold–blooded animals.
The USPS: https://pe.usps.com/text/pub52/pub52c5_008.htm
And it's been used for this (well, technically, it was the US Post Office, when it started, not the US Postal Service) for more than a century.