So to weigh in from the POV of Rheingov. (Separate hat from being a Dev in this case)
To me, the cut-off is pretty simple. If a ship can challenge a reasonable cruiser player in the course of an INRP contraband scan stop, it must be restricted. And I don't mean run away (which for example a freighter can easily do). I mean take on the cruiser in combat and force it to retreat.
I would ask you what reasonable government would allow anyone to operate anything like that without a license? E.g. imagine if in the current world, anyone could just legally buy a tank and drive it on a highway. I understand that we're dealing with a game world, but that to me is the point of govs. If you want to "gameify" such a dynamic, then remove all laws that ban ship classes.
Arguably, such a move would indeed increase activity, as it would force lawfuls to log more people to challenge an unwelcome corporation. For example, if a DSE convoy is allowed to fly Cruisers (disregard ID lines for a sec) to support its Light Arms hauling, RFP/RM/MND would probably need to log upwards of five people to be able to enforce its laws. But is this a reasonable INRP situation? I currently don't think so. After all, we could just do away with all ID restrictions as that would probably increase player numbers too, but you gotta draw the line somewhere.
Now for the second part, about licenses. Let's move past the length of review for these, because that's a separate problem.
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Rheingov has a pretty simple decision making process for requests: how much RP was invested in making the request? And, is the request reasonable within a house which is essentially a police state? Note the order of the decision making - if barely any rp was invested, the app is not considered further. If rp was invested, the app is considered within the general context of current house policy.
So if you are salty about your license app getting denied, first ask yourself: did you contact RFP, RM, or MND with your request? Did you attempt to have them make the app on your behalf because it would be beneficial for those factions, or to the military benefit of Rheinland? Alternatively, did you contact DHC or Kruger to ensure that you're not competing with their operations? Did you provide them with a reason why your request would be beneficial to those factions, or to the economic benefit of Rheinland?
If you answer no to any of the above, please tell me why your app should be accepted? Why should a House government give you what you're asking when you've made no inroads into becoming a known entity within the House? Why should you get the benefit of your request while providing no benefits (or even active competition or security concerns) to existing House factions?
[/rant]
Take Bristol for example. If they do the bare minimum of describing how Bering is still being developed, and they can export their industrial output in Bulwarks because they're always in danger of Unioner raids, etc., they will be granted the license. After all, they are already a known entity - note their exemption for hauling Milsal. Take a look at the recent approval of the OS&C Amaterasu. Can you generate this type of RP (edit: just the comm, not the event) before submitting your application? If not, why do you deserve the license?
Finally, as long as I am in gov, I will always argue against monetary licenses for anything besides POBs. That's not to say that you can't pay say DHC to build you x ship, and get a license for it that way. But I hope that we will never charge people credits for approving their license. Only RP.