Workmates are generally not counsellors and people at work are not our friends.
And even among our friends, many do not have the emotional capacity to counsel someone or hold space for someone who releases traumatic information to them.
So people often do not ask how someone is for that very reason - they cannot deal with it, do not know how to handle it or simply do not want to discuss it and do NOT wish to open the door to the other person discussing their feeelings.
They can have extremely good reasons for not wanting to do this.
It can also just be that they don't know what to say.
I have mental health/counselling training and experience and will always ask someone if they are ok, offer a kind word if they look stressed/down or I have heard they have had bad news - because I know how that my training means I am unlikely to make a massive misstep and I know what resources to search for and how to do it if the person needs more help than my shoulder.
But I always tell other people NOT TO DO THIS if they are not sure they can cope with it.
If a co worker asks how someone is doing and they start to tell them something raw, or real it can quickly become extremely distressing to the person who only wanted to be kind. Shutting down a grief stricken person because you cannot deal with their pain is actually more traumatic to the person than just not asking them anything in the first place.
Not to mention, grief can make people unreasonable and selfish - which is entirely and completely understandable and normal - HOWEVER the person without counselling/grief counselling training might react badly to comments the grieving person makes too.
If in doubt, say nothing is far better than saying the wrong thing or having someone trauma dump on the wrong person.
I do think it is reasonable to expect a "Sorry for your loss" from co workers - but though it is reasonable to expect it, many won't give it anyway and though some are being selfish, many have very good reasons. You do not know what they are going through either.
I should have said this earlier - I am sorry for your loss. Please contact a counsellor to help support you through this enormous loss.