The guy also misses the point that packets can be dropped because of integrity check failures: if the packet has been altered in some way (cosmic ray, WiFi interfering with microwaves or whatever), then the checksum fails and the packet is dropped.
Actually, the causes of packet dropping are (AFAIK) exactly the same as in TCP. But in TCP, dropped packets are sent again.
One exception though: in UDP, delayed packets won't be waited for long before being dropped.