"CanPickUpLoot" is inconsistent with other boolean tags

The "CanPickUpLoot" tag is different from other boolean tags in a way I can't put into words. Let me explain.
1. Run /summon zombie ~ ~ ~

{CanPickUpLoot:1}

2. Run /summon zombie ~ ~ ~

{CanPickUpLoot:1b}

3. Throw two items on the ground
What is expected:
Both zombies pick up an item
What happens instead:
Only the zombie that has the tag set to "1b" picks it up. All the other tags work if you just type "1", so what's the deal with this tag?