It’s interesting that some of the papers you quote say that the research has found mixed results, rather than showing definitive results. It suggests that the research isn’t as black and white as you claim.
I didn't claim the full amount was priced in. I said that it is partially priced-in, which is what the research shows, and is likely due to the fact that international investors don't receive the franking credits.
If over decades 40-80% is priced in, is the fact that it is not an exact number somehow saying that franking credits are not being priced in?
If you look at non-Australian share prices, they doesn't fall by
exactly the amount of the dividend paid out when they go ex-dividend, sometimes it's more and sometimes it's less. This is because the rest of the time when dividends are not paid out, the share price moves up and down. The market is reacting to new information about the company, sector, or market it is in. When a share goes ex-dividend, these forces are still in play, and therefore the share price doesn't drop by
exactly the price of the dividend. This doesn't mean it's somehow not "black and white" that dividends are priced into by a drop in share price. In the same way, just because it doesn't drop by an exact amount each time doesn't mean that franking credits are not priced in.
This amount (however much it is), means that for the franking credits you get in your hand, part this amount is lost due to a drop in share price.
If you mean that it is not black and white
how much it is priced in, then yes, by the nature of not all of it being priced-in due to international shareholders who don't get franking credits, and with all the other information being priced in and changing constantly, it is impossible to tell exactly how much.