The European market for blisters is larger than that in the United States. They use more-opaque materials, which they claim are less attractive to children. Their culture has been more accepting of blisters as the preferred method of packaging. The European community also has stronger environmental reasons for using blisters, and manufacturers are penalized for introducing excessive material into the system. They are just more frugal in their use of materials.
Blisters come in the preferred multiple for the specific country.
For example, Italy prefers multiples of seven. Another growth area for blisters is clinical trials. With the increasing incidence of clinical trials, many of which require complex regimens, more pharmaceutical companies are employing blisters. For a dose range study where the patient is taking four tablets a day or a placebo, the only way to do it is in a blister. It is hard to tell a patient to take one tablet from this bottle, then one from this bottle, etc.