At 40 scratches per ticket. That means 3200 SG, which is actually more than the 2920 SG one can buy at once using cash, and it serves as a barrier of entry that probably stops a lot of people from taking even a dip in the SG scratches.
For example, I only want 3-5 items, and out of these 3-5, only 1-2 are really what I would go for, from the upcoming Mother scratch, and there's simply no way I'm going to spend 3200 SG on it. So I am just going to give up.
The fact that they are not tradeable, also means we can't put in 800SG and hope to make exchanges with other players either via trade or the market.
But if the threshold was lowered to 10 scratches per ticket, then anyone who wants even just 1 item has a reason to consider spending 800 SG. For people who want 3-5 items or more from it, it's conceivable that 1600 SG for a ticket would be worth it.
AC sitting at 30 scratches is fine, because items are tradeable. But that doesn't apply to SG scratches.