"A box of disposable mice where the high failure rate is an expected part of the cost."
The '30 Pack' spec means you are buying disposable hardware in bulk. It is a commodity purchase where you treat the mice as consumables, not durable equipment.
This is for system administrators who need a stack of cheap, throwaway mice for server racks or temporary setups. It may also suit schools for standardized testing, provided they budget for a significant number of duds.
Anyone looking for a reliable daily-use mouse should look elsewhere. If you need exactly 30 working mice for an event, the reported failure rate makes this a risky purchase without ordering significant overage.