Tempting to casually link secular declines in economic growth rates to other things you feel strongly about, say, fiscal austerity, for example, recently in the UK.
Good to start from this Table in the paper by G. Ventura, J. Villaverde and W. Yao: in per capita terms (line 2) or in per worker terms (line 3) long-run growth rates are not all that different across countries, when compared to raw GDP growth rates (line 1).
Between 1991 and 2019, the UK had a growth rate of GDP per working-age adult of 1.62% compared to 1.65% for the US. France's growth rate is 1.33%. Japan's is 1.39%.
Of course, the levels of GDP per working-age adult are very different across countries.
nber.org/papers/w31914