I know the Victorians loved to exaggerate the scale of their monuments... but even so that image of the town hall takes the cake!
See https://www.expedia.co.uk/Leeds-Town-Hall-Leeds-City-Center....
The other difference is greater civic pride, and a different sense of aesthetics among the people who made the decisions. In absolute terms all those towns with nice old civic buildings are much richer than they were in the 19th century - but any new buildings are almost guaranteed to be hideous.
But Empire was important. There was more money concentrated in fewer British hands than ever before, or ever since. "Empire" is also a broad term: the Industrial Revolution, originating in the Midlands; steam power, which was exported globally; and of course, the slave trade, which Britain both catalysed and then worked hard to destroy. They all had their part - they were drivers and benefactors of Empire, and they all put plenty of cash into a few well meaning citizens' pockets.
Small towns that didn’t have a town hall or courthouse or other civic buildings built by the 1930s or so tend to have government structures that look like (or are in!) strip malls. Or look like cheap funeral homes.
We’re “way richer now” but all our nice buildings are from when we were “poor”. That even goes for commercial and industrial buildings. The stock of nice 5-15 story brick buildings that can be renovated into attractive apartments is basically fixed (actually, declining), because we don’t build anything that attractive and durable anymore.
Similarly, it’s sometimes worrying how much of the very-nice infrastructure in our parks (state and national, both) was built by 1930s “New Deal” programs and hasn’t seen more than maintenance since. These are treasures we still enjoy today and we haven’t seriously invested in more of them in most of a century.