Inventory id - still need "minecraft:" in syntax

I'm not sure it a "bug" but while on other commands, we don't need to use "minecraft:" in front of name of blocks, i post this.

While using the command

testfor @p {SelectedItemSlot:0,Inventory:[

{Slot:0b,id:minecraft:torch}

]}

The command don't work if i don't mention "minecraft:" before torch

But on this command

execute @a ~ ~ ~ detect ~ ~-1 ~ purpur_block 0 effect @p 1 2 1

I don't need to write "minecraft:" in front of "purpur_block" (but this command still work with "minecraft:" in front of it).