This is more of a language question than anything else.
I’ve noticed that with many products found in a grocery store, the number of items found inside the package is labeled in “counts”. For example; “Sugar packets, 150 count” instead of “150 packets”, or “Flexible straws, 100 count” instead of “100 straws”
I’m curious about the origins of this practice. It’s language we don’t use every day, for example, “There are ten count cars in the parking lot” or “The printer can store 150 count sheets of paper.”
Because in a listing, such as inventory, or a vendor’s price list, you have a column that lists unit of measure.
It’s going to show oz., g., ml, lb., etc. Count or CT is used when it’s a specific number because it’s standard, rather than inserting straws, sheets, pens, packets. You can glance at the “unit of measure” column and recognize one of a handful of options, rather than have to read a whole word and actually think about what it says.
Other options is dz. or dozen and each. or ea., which is almost exclusively used for 12 count. You also might see gross or bushel although the latter has probably fallen completely out of usage and I’ve only seen gross (12 dozen or 144) used on larger bulk items and fireworks.