Yes, I know. I had a hard time finding many. Another strange issue, the corner relief area is not manufactured beyond a certain size for many manufacturers. Snap-on is one of the few who continues with their flank drive regardless of size -- smart, maybe pricey too ??? Anyway, just saying you don't need them is and opinion not an answer why they don't make them, except for a few. I could counter that opinion, by asking why then some European mfrs are making them?
Stahlwille, Hazet, Beta, Facom all do chrome 6pt in 3/4 drive, there is probably more but thats what I have seen personally.
The Stahlwille has relieved corners, at least up to the high 36mm as that the biggest I have of those.
3/4 sockets last a long time, good makes that is, they are a buy once tool for most who use them professionally, lots of old sets out there you can pick up relatively cheaply but they will be 12pt, because most sockets were 12pt in the past.
12pt makes the most sense for 3/4 for hand use, your almost always need to use a breaker or sliding T bar with a pipe to break large bolts loose, so need the 12pt to get on the bolt, the ratchets are expensive, clunky and have big heads (modern ones are better), so you dont tend to break bolts loose with them.
Plus as I have already said impact wrenches are used wherever possible with 6pt impact sockets, so if you do want a 6pt for hand use you can just use them. Save buying an expensive set of chrome.
If you can round large bolts, say a 30mm with a 12pt socket by hand, your a better man than me, I cant unless the cheater was very long, usually only happens when using a floor jack or excavator boom to turn it.
My own are a mix, but I have more 6pt, I bought whatever good sockets I could get a good price on.