[Scirra should] determine whether their products do indeed have bugs without placing a lot of that burden on customers...
Unity devs... often provide steps for me to check if something is a bug in the product
So it's OK for the Unity devs to send you steps to check if something is really a bug, but not us?
Perhaps one of the differences is that Construct 2 users are often either inexperienced or non-technical, and are prone to seeing their own mistakes as C2 bugs, or just making vague bug reports which are impossible to follow up on. It's conceivable that the higher technical requirements for using Unity mean that the majority of their bug reports are high quality reports which really are bugs, whereas it is definitely the case that a significant proportion of C2 bug reports are not bugs or not actionable reports. This would mean Unity can afford to make the odd exception to invest in testing and debugging only to find it was a user's mistake, but we cannot, since it happens too often.