I said this in another comment but it seems like these cases are assuming a long time passing between the SAFE and the priced round. Not sure if DelaneyM and pmcaffey are referring to that.
If SAFE is a way to start what would be a priced round (a few months), then your numbers would tell a different story. You getting to invest $1M and $10M cap, and then the company raising at $20M valuation later, means that you got an unfairly low priced deal (assuming company's valuation wouldn't naturally double in those couple of months).
In short timeframes (SAFE -> Priced rounds), its hard to imagine something other than discounts being fairer to all parties concerned.
In longer timeframes where the next priced round is a Series A, an year later, your point stands and is well taken.
If SAFE is a way to start what would be a priced round (a few months), then your numbers would tell a different story. You getting to invest $1M and $10M cap, and then the company raising at $20M valuation later, means that you got an unfairly low priced deal (assuming company's valuation wouldn't naturally double in those couple of months).
In short timeframes (SAFE -> Priced rounds), its hard to imagine something other than discounts being fairer to all parties concerned.
In longer timeframes where the next priced round is a Series A, an year later, your point stands and is well taken.