7 years of secondary education in England - 5 years to GCSE, studying a braod range of around 10 subjects, 2 years for A level specialising in 3-4 subjects in depth (though now with the fiddly A2s mixed in, but didn't used to be til relatively recently).
In Scotland its 5 years to Highers, then you can do more Highers in year 6 or Advanced Highers. Advanced Highers are equivalent to A level, but it is possible and in fact common to get into a Scottish university without doing Advanced Highers (which used to be called Certificate of 6th Year Studies).
UCAS give an A grade Advanced Higher 130 points, and an A grade Higher 80 points.
www.ucas.com/ucas/undergraduate/getting-started/entry-requirements/tariff/tariff-tables/1021
An A* A level earns 140 UCAS points, a grade A AS level without the follow-on A level 60 points.
If you are a Scottish student who gets your offer to study for your degree based on 280 UCAS points, you might have only studied your subject to Higher level but also have 4 other Highers in totally different subjects. The breadth of your education might be better than somebody who has studied the subject to A level, but the depth will not be as great.
Scottish students who have done Advanced Highers will have studied in similar depth to A level students, but students who get into university after simply doing more Highers, either in order to make the points score or to do more subjects will not have done so at all (many do Highers in 5th year and then more highers in other subjects in 6th year, not Highers then Advanced Highers - there is no obligation to do Advanced Highers and many do not do so.)
The sytem based on getting into university after studying Highers only (not CSYS/ Advanced Highers) is what makes the 4 year degree logical.
The first year of a "school" subject like English is not as advanced as the first year of a degree from a respected university in the UK. I went to open days in Scotland and the pace and content of the first year begins at a similar level to the upper 6th, which is why (at least 25 years ago) it was very common place for students predicted 4 A level grade As including the subject they were applying to study to be offered direct entry to the second year, contingent on the A grade in the relevant A level (and As or Bs in the others).
The Scottish system has strength in continuing breadth of study for longer, but 4 year Scottish degrees are not "better" than 3 year English degrees - they do not assume the same starting point as a 3 year English degree course, at least in traditional subjects requiring a same subject A level at grade A (A* now) or sometimes minimum B for entry.