Hello Willy
When you have a /30 network, you’re right, there really is no use for the broadcast address, since it would be the same as communicating with the other host on the network, since only two hosts exist. However, because the broadcast functionality is one that must function on all subnet sizes, it works the same regardless of the size of the subnet. There is no exception to the way broadcast works for /30 networks.
However, having said that, it is possible to create a /31 network on some networking equipment. Cisco supports such a feature. You can have an IP range of 192.168.1.10/31 for example, and this subnet would have a range from 192.168.1.10 to 192.168.1.11. This would have no network or broadcast address, but would function as a point to point link. This is a slight violation of the functionality of IPv4, but some vendors do support it, in order to save on addresses when implementing many point to point networks.
I hope this has been helpful!
Laz