Technically Apple isn't lying or deceiving anyone. 1024 bytes is 1 KiB, not 1 KB so:
1 TB ≠ 931 GB
1 TB = 1000 GB
1 TB = 931 GiB
The problem is we often use MB, GB, TB, etc. when we really mean MiB, GiB, TiB, etc.
A 64 GB iPhone actually has 64 GB of storage, but only has 59.6 GiB.