Boats, boat with chest, bamboo raft or bamboo raft with chest travel fast on mobs.
Mob type:
Boat
Boat with chest
Bamboo raft
Bamboo raft with chest
Minecart(all)
Armor Stand
End CrystalShulker
Falling Sand / AnvilNoAI mobs
Players
Code analysis by @unknown can be found in this comment.
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This issue relates to MC-96195

Confirmed for
16w14a

Please link to this comment in the description
The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.
The reason why this happens is because the boat is treated as if it is in air, which means its motion factor is set by the method net.minecraft.entity.item.EntityBoat.func_184450_w()
to 0.9, which is also used by water. A new net.minecraft.entity.item.EntityBoat.Status
called for example ON_ENTITY
would be probably required to solve this.
Can confirm in 20w48a. Here's some commands to help reproduce this bug.
/summon minecraft:creeper ~ ~ ~ {NoAI:1}
/execute at @e[type=creeper,sort=nearest,limit=1] run summon boat ~ ~2 ~
Can confirm in 21w03a.
Can confirm in 21w05a.
Can confirm in 21w05b.
Can confirm in 21w06a.
Video attached.
Can confirm in 21w07a.
Can confirm in 21w11a.

Can confirm in 21w15a

This is probably to do with the drag present in water that isn't present on land.

Can confirm in 23w06a

Can confirm in 1.19.4 Pre-release 1.