This isn't that different in the US. Algebra 1 to Algebra 2 to Precalculus to Calculus is a sequence that's taught over many years and there's no big dump. Geometry is the only exception from that sequence (unless you're counting Statistics or Computer Science, which are generally optional). Most students that are applying to competitive colleges are generally going to take a math course every year - there's no big dump that you seem to be envisioning.