There are certainly countries where a translation of "16 o'clock" or similar is the default way to say that time. France is one I'm familiar with. In Britain,

There are certainly countries where a translation of "16 o'clock" or similar is the default way to say that time. France is one I'm familiar with. In Britain, people reading out an important time presented in 24h format (like when discussing booking a flight) will usually read it out as fifteen thirty etc.