Edited)srowen,
Unfortunately this could become a rather lengthy exchange and I have limited time (and posts), however, as one example of an advantage of indirect:
Create a direct and an indirect code for a campaign:
Post that code on a billboard in Time Square.
In 3 months when your campaign changes to that of a new product, change the content that you are linking to.
In order to accomplish this via the indirect method you retain the original code and merely change the URL on the backend that the code points to. You retain the "same code" for the new ad without changing the billboard, thereby saving time and money.
In working with direct codes the process changes. You either need to embed one generic link within the barcode that can then be directed to the campaign in question, except when changing your campaign you would go through additional steps to file your old campaign in a way that is easily found later on when you need it.
Should your campaign manager resign from the company I would hope that manager's filing method was clear and adequate if an old campaign needs to be unearthed again. The new hire may have no idea what that campaign was filed under. Perhaps you have addressed this in an online system, however, to my knowledge managing the campaigns is considerably simpler, clearer, and more easily managed with indirect.
Btw, does Google have a KeyWord search (to type the barcode number or key word) that can be used in place of a barcode should the consumer not have a camera?
As for security, without engaging a lengthy dialogue on the subject let me simply say that the IATA specifically enjoys indirect over direct due to the enhanced security associated with the codes.
There are other apps I would truly like to discuss with you, however, you are a Neom competitor and I certainly DO NOT wish to arm you in any way :) I prefer NOT to provide you with items on which to focus.
Best,
BC