The difference in the amount of information shared by clubs is typically down to whether they are publicly traded or not. If they are public, then there is more information they need to disclose in their accounts and some details they can't make public for legal reasons.
As for injuries, for some injuries, there is no timescale except "wait until it's better". The club certainly don't owe us that kind of information and it probably violates EU privacy laws if they communicate health details without the players consent.
I'm more interested in the available players and how they perform, to be honest. If Moult and Skippy start in Saturday it doesn't matter if Fletcher is out for a week or a month; he will have no influence on the result.