"Drivers Triangle" appears to be a "park" so small it's not marked in green on Google Maps. It's also in Penrith which is like a 40 minute drive from the city. Rea Reserve is similar. Astrolabe park is... a park, but it's not in the top 10 parks in the city.
Same for London. Belsize Wood Nature Reserve is a very odd pick a long way on public transport or driving from the centre, and despite living in London for 10 years I've never heard of it. Meanwhile Hyde Park, Regents Park, St James's Park, Battersea, Greenwich, Green Park, ... there are so many iconic parks in London.
My advice would be to curate these per city. It's going to be much easier to just decide which the top parks are for any given city, and with a few hundred cities you'd get pretty good coverage of queries.