Let's do maths

Domestic:
Transformers 1: $319 Million
Transformers 2: $402 Million
Transformers 3 (3D): $352 Million
Transformers 4 (3D): $245 Million
Transformers 5 (3D): $102 Million (still going)

International:
Transformers 1: $708 Million
Transformers 2: $863 Million
Transformers 3 (3D): $1124 Million
Transformers 4 (3D): $1104 Million
Transformers 5 (3D): $432 Million (still going)

Domestic:
Pirates of the Caribbean 1: $305 Million
Pirates of the Caribbean 2: $432 Million
Pirates of the Caribbean 3: $309 Million
Pirates of the Caribbean 4 (3D): $241 Million
Pirates of the Caribbean 5 (3D): $166 Million (still going)

International:
Pirates of the Caribbean 1: $654 Million
Pirates of the Caribbean 2:$1066 Million
Pirates of the Caribbean 3: $963 Million
Pirates of the Caribbean 4 (3D): $1045 Million
Pirates of the Caribbean 5 (3D): $710 Million

In both cases what we're seeing is that both franchises found their international footing with later pictures, while both peaked with their second films domestically (as likely people loved the first film most and were disappointed with subsequent entries). If we remove 3D from the equation it looks like Pirates dropped around or over a hundred million with each subsequent sequel (until the most recent) while Transformers has a similarly precipitous return on investment. Domestically.

There have been a number of stories about how this is a bad summer for franchise films, but graphing these sequels shows that America had already lost most of their interest in these films and if the studios thought there would be a different result from these films, they would have to be dumber than our sitting president. They were not. America was an afterthought.

But then also, this:

The first film where America counts for most than 50% of the gross? The LEGO Batman Movie at number 16. At number 12? The Mummy, which is being treated as one of the biggest bombs of the summer (that said, it may lose money, but let's also do some quick comparisons. If you look at the worldwide chart outside of the Mission Impossible franchise, this is a solid WW gross for Tom Cruise, tracking a little behind Edge of Tomorrow, which is getting a sequel) . Seven of the top movies for the year (so far) made over eighty percent of their money overseas.

Similarly
Cars: $244 Million
Cars 2: $191 Million
Cars 3:  $121 Million (Still going)

International:
Cars: $462 Million
Cars 2: $562 Million
Cars 3: $174 Million (it looks like this hasn't opened in most territories).

Pixar knows what they're doing.