Ola Hallengren Transaction Log Backups of System Databases
Per this Microsoft documentation:

For backwards compatibility with earlier versions of Microsoft SQL
Server, the recovery model of master can be set to FULL or
BULK_LOGGED. However, BACKUP LOG is not supported for master.
Therefore, even if the recovery model of master is changed to full or
bulk-logged, the database continues to operate as if it were using the
simple recovery model.

So that's why you can't get a transaction log backup of Master.
From that same document:

Best practice:  We recommend that you create only full database backups of model, as required. Because model is small and rarely changes, backing up the log is unnecessary.

While that doesn't explicitly say that SQL will prevent a transaction log of Model from happening, it certainly recommends against it.
Note: That's an old version (2008 R2) of the documentation. New versions (I checked 2017) don't repeat the detail about Master, but they also don't contradict it.