/damage does not trigger Thorns

Thorns does not work when one entity damages another via the /damage command.

To reproduce

1. /summon minecraft:giant ~ ~ ~ {attributes:[{id:max_health,base:1000d},{id:knockback_resistance,base:1d}],equipment:{chest:{id:diamond_chestplate,components:{enchantments:{thorns:3}}}}}

2. /summon minecraft:iron_golem ~ ~ ~ {NoAI:1b}

3. Repeatedly run /damage @n[type=minecraft:giant] 1 minecraft:mob_attack by @n[type=iron_golem]
   ❌ Thorns is never triggered

4. /data modify entity @n[type=minecraft:iron_golem] NoAI set value 0b
   ✅ The iron golem sometimes takes Thorns damage when it attacks the giant