Minecraft – How long does it take to drink a water bottle in Minecraft

Silly answer: The resources are being shoved along the ground and dragging on it (they're not floating, after all), whereas the player is at risk of falling over, so must walk with the current to keep their balance.

Actual relevant information: Note that resources move far faster in a water current on top of ice (faster than the apparent current!), and slower on soul sand. This indicates that the slowness of resources is mostly caused by friction. Maybe the player inherently "has less friction", and therefore moves faster.

[I say "resource" rather than "item" to refer to dropped things because of the convention that "items" are those things-you-can-carry which are not blocks (so resources are both items and blocks), and Notch called them resources at least in the past.]

Apparently they still work, but are slower and more difficult to build.

As of Beta 1.5, you are now required to look at the corner between the water and the ladders to even go up the water ladder, and the bottom of the ladder now requires three consecutive ladders without a gap. Going up a water ladder is slightly slower than before, but it's still significantly faster than regular ladders. Also as of Beta 1.5, Minecraft will sometimes recognize the player as "in" the water causing an annoying delay to climbing ladders.

As of Beta 1.6, water ladders are harder to build, slower and more difficult to use, but still allow faster vertical motion than ladders.

Here is a tutorial for 1.5 (at about 2:00 it talks about pre 1.5 water ladders and how to make them work again)

Here is a tutorial for 1.6.6