Emilio, that's right....but that's not all the part of the story..
In south america... Low income families still use alot of bar soaps and or flakes also, you may confirm this, and as we all know, the signs that tells us when our wash solution with soap is ready is when it starts to have a nice layer of suds, and more suds there is and stronger is the wash solution, so detergents over there tend to re-create the same conditions that tells us when the solution is "soapy" enough...so unlike elsewhere in those countries they do not put anything in their regular products to reduce the foam.
While it is not a problem in top loaders and twin tubs, it may become so in front loaders in certain cases....that's why for them is best reccomended to use controlled foam products otherwise called low suds...that avoid possible oversudsing problems.
Over here hand wash/twin tub/top loader products are just the same, and so are also regular products in the USA...even though many modern (non HE ) do have now a bit of defoaming agents too that limit and just does not let them suds all the way like south american does, , that instead still foam freely without something that brakes it...older regular products indeed generally tended to foam just like these as they didn't have any defoaming agents, but didn't miss products that had as peculiarity the low foaming, i recall Dash, suggested infact to be used in front loaders...
You may see like naturally every product made of surfactans foam, just think at the dish soap....so is in the nature of soaps and detergents to foam, what changes is the addition of defoaming agents...
I know the power of a detergent is not dictated by the amount of foam it produces, but in all honesty, I have always found high sudsing products to be different and better than low sudsing....do not know why, also, i do not have problems in rinsing at all, since after first spin it usually is all gone and do hot have traces in the rinse....
Speaking of rinse
Many people think of low suds detergents to be easy rinsing because of this reason, but the lack of foam in rinses is not a sign of good rinsing, you may well still have detergent in your rinse, but not see it because it won't produce foam being a reduced foam product...one of the sure signs instead is water color....if it's torbid it still have detergent in it, if it's clear then it's well rinsed....