I suspect that this is because this site is much larger that others.
This site has 152,000 members.
Some sites have only a few hundered. I suspect the extra load on the servers that would be generated by such changes would grind it to a halt.
The sites i have seen that give the extra data you mention end up saying 'guests 24' 'registered members 4' etc...Not hard to display when only in single or double figures.
How many now here I cant say, FE would have to be consulted.