Because when you meet up and say "hi, how are you?" that's not the forum for a "well actually..."
It's a salutation.
My brother and my mother both answer this question honestly (the following are both summaries of real conversations).
Me - "Hi, how are you?"
Mum - "Oh, same as usual. X is still of work at the moment and they won't get a temp in to cover them which means we've got to all cover her work. I wouldn't mind but I've had to set up some new spreadsheets this week and I'm the only one who can put the formula in so I'm the one who always gets asked and the Snr Mgmnt have no idea how much pressure they're putting on us...."
Brother - "How am I? You're asking how I am? How do you think I fucking am? My grandma died at the start of the fucking year, (er my grandma too) the economy's fucked, TTC isn't working and we've got no fucking money to pay for IVF... Don't ever talk to me about your fucking children ever again, I don't fucking give a shit about you and your fucking children; my parents got divorced (18 years ago) and don't give a fucking shit about any of us; if we hadn't had to pay for our wedding ourselves we'd be able to afford IVF. Then again, if someone had given enough of a shit to help pay for the wedding, we'd have got married sooner and then X getting pregnant might not have been so much of a fucking issue..."
Frankly, I don't want to hear it. If I greet someone with a "Hi how are you?" I'd like to hear "Oh you know, not too bad. You?" at which point I can say, "yeah, you know, the same. Do you want a drink?" and then other stuff can come out in the course of conversation.
And breathe....