Frequency of vines on lush caves is very low compared to cave vines

Vines seem to generate at very low frequency on lush caves. Compared to the amount of cave vines, patches of vines seem to randomly generate on the ceiling or walls with only a single vine, similar to glow lichen.

In a relevant screenshot from MC Live 2020, the lush cave had a vast amount of vines, which would be the expected. However, this doesn't seem to be the case since the biome was introduced.

How to reproduce

1. Generate a single biome world of lush caves.
2. Find a relatively large-sized cave.
3. Notice the vine generation frequency.

Observed result
Barely any vines generate on lush caves, compared to cave vines.

Expected result
Lush caves would generate with a higher frequency of vines, similar to cave vines.