Why is bread uncountable? How do you describe the "three breads" in the picture?

Solution 1:

In Britain, a loaf of bread would generally be anything big enough to be cut into multiple slices of bread, e.g. for making sandwiches. So this is a loaf, and at least the one on the left of this picture is a loaf.

The items in the second picture that are small enough to be just 1 - 2 portions, would be rolls. Buns tend to be sweeter than rolls, although a soft roll containing raisins and currants is often called a currant bun.

Normally, bread is an uncountable noun. Having said that, searching Google for "three breads" does give many hits. Specifically:

1. "Three breads" may be used to mean "three types of bread", e.g.:
   Salmon and Scrambled Egg with three breads here
   BLT choice of three breads, mine was a baguette here
2. The term is used biblically and in sermons, etc., e.g.:
   “Three Breads” - John 6:24-35 here
3. There appears to be a place in New Zealand, named "Three Breads & 2 Fishes"

The search also revealed a forum discussion here on the subject "How to ask for two 'breads'", which included the following comment:

Sorry, but I have never heard anyone say "2 breads" when 2 loaves is meant.
The only time that "breads" could be used, is if different types of bread is meant.
For example.
I have to buy three breads: a loaf of gluten-free for Rose, two loaves of sour-dough rye for Daisy, and a white loaf for Hyacinth.

I'll leave others to search further if desired.

To address the final sub-question, "Can the word servings be used?":

One can talk of "servings of bread", but the items in the picture would not normally be described to in that way.

The expression "servings of bread" could be used in a restaurant, but its meaning would depend on how the restaurant serves their breads. [I have intentionally used the plural there, which I think is acceptable in this context.]

A serving of bread would be the amount of bread that the restaurant normally serves for one person, such as two slices of bread; one bread roll; a few bread sticks; etc.. You would refer to three rolls as "three servings of bread" only if the restaurant normally served one bread roll per person.

Solution 2:

The accepted answer is correct, but I think an answer that is both more general and simpler, is that words are not countable or uncountable, senses are countable or uncountable.

In this case, bread in the sense of the stuff you get when you bake bread-dough, is uncountable. You can't say "three breads" in this sense.

Bread in the sense of a sort of bread in the first sense, is countable, and so you can say the picture shows three breads (a poppy-seed bread, a sesame-seed bread and a plainer bread).

So far this is all covered by the accepted answer here. What's worth adding, is that this goes for all other words too: In talking about countable or uncountable, one must address senses of words, not words themselves.

Solution 3:

Bread is a category of substance, like plastic; you don't say "three plastics" to mean three pieces of plastic, but to mean three kinds of plastic. The distinction between a loaf and a slice is what you've made that substance into; a loaf of plastic would be odd, but a bread bowl is an interesting novelty.