I didn't realize that. I wonder if that is because they are more popular over there? Is it a market thing?
Regarding aluminum, can it be made as strong as steel inch:inch, or do you have to make it thicker? Are repairs as easy, I wonder? If so, it would seem to be the material of choice.
Where steel comes into its own is that it is very strong and stiff for any given cross sectional area. There are few if any boat building materials that come anywhere close. But steel is also very dense. Because of that an equal weight of any other boat building material has a much thicker cross section. Since the properties of materials (sheer not withstanding) are calculated as the square, cube or fourth power of the thickness (depending on the purpose of the calculation), it turns out that if you believe in the science, when viewed solely on a pound for pound basis, steel is one of the weakest boat building materials.
Where steel comes into its own is that it is pretty cheap relative to its strength, and it has a very high abrasion resistance.
The weight issue often gets dismissed by traditional cruising sailors, but does come into play in very real ways that directly impacts cruisers. When a boat is designed, its hull lines lock in a specific displacement and rate of displacement gain with additional immersion. In other words any given hull shape can only tolerate carrying a given amount of combined weight of hull, ballast, rig, hardware, engine and consumables, and the question then becomes how do you divvy up this weight between the various parts of the boat and what it carries.
If you compare two boats of equal strength, but constructed of different materials, and the hull of one weighs 40-50% more than the other due to the material (an increase which may be as much as a 10-20% of the overall displacement of the boat) that additional hull weight has to be accomodated somehow. That 'somehow' could be a mix of decreased ballast weight, lower carrying capacity, smaller tankage, less interior appointments and the like. And these trade off's translate to a smaller range, less stability, more roll, and so on. And none of that is good for a cruiser.
But, to answer your question, the case of aluminum it does take greater thickness to achieve the same bending, stiffness and puncture strength. But, if you believe the science, even with that greater thickness, an equal strength aluminum hull will be lighter than the comparable steel boat.