Less efficient in terms of transportation - you’re shipping a whole bunch of water that doesn’t add to the cleaning, which takes up more space, so less soap is being carried, etc.
Plastic packaging vs paper packaging for some solid soaps.
Some shower gels have microplastics for added abrasion, but so do some soaps tbf. Still, less good at cleaning because solid soaps involve more scrubbing.
Often can’t get everything out of the bottle. Some bottles don’t allow you to take the cap off and fill them with water to fully empty them.
I don’t live in america but good to know 👍