That's a stupid grammar rule anyways.
Let's say we are talking about the driver of the truck instead of the truck itself. Let's say the driver is named Jeff. We could say "On Jeff's way to Dunedin". Jeff is a proper noun, the way belongs to Jeff, so we use an apostrophe to indicate ownership
But if we go back to talking about the truck, we use a pronoun because the truck doesn't have a proper name. All of a sudden we have to say "On its way to Dunedin" even though the way still belongs to "it" ("it" being the truck") but we can't use an apostrophe here to indicate ownership for no apparent reason. It's total inconsistency and it's ********.
example 2) I have a cat named Frank. It has a toy. How on earth does it make sense to write "Frank's toy" but when I use a pronoun all of a sudden I write "its toy". Garbage rule is garbage