Leptospirosis is a significant problem worldwide, as 2xw points out. It's more common in warm regions and, as well as occupational exposure (which includes caving) there have been several major outbreaks in Central America after floods. With climate change and increasing urbanisation of the countryside, this is likely to get worse, not better. Most cases occur in developing countries with small health budgets, so any vaccination programme would have to be cheap. In wealthy countries, the incidence is low and it would be difficult to justify widespread vaccination on economic grounds. Most of the cases I've seen haven't been in people at very high risk (eg sewage workers) but have been in farmers, gardeners and soldiers who weren't indulging in particularly risky behaviour.
There are numerous species (increasing all the time) and over 300 serovars (which are immunologically distinct, even if they aren't different species). Historically, individual vaccines have tended to be active against only a few serovars, which limited their usefulness. The implication is that one would need to create a large number of separate vaccines to achieve wide coverage, which would be very expensive (as would be the cost for each vaccination).
What is interesting about this new vaccine is that it has the potential to be active against a very wide variety of species. Potentially, one vaccine could be developed which would work in most countries. The economies of scale would allow individual doses of vaccine to be cheap. The fact that it appears to be a single dose vaccine makes the logistics of a vaccination programme much simpler than a multiple vaccine schedule (eg Covid).