This is a real thing and a very good point.
To give a personal and recent example, I was asked on Thursday of last week to jump in at the last minute to help finish someone's feature over the weekend. I'm not sure of the details for why their DP became unavailable. The filmmaker had a shot list for Saturday that was 15 pages long taking place in 7 different locations - and both I and the other guy they brought in had a hard out at 4 or 5 in the afternoon. Sunday's agenda was similar, but without either of us needing to leave. We didn't finish the list for either day. Likely, we'll be shooting again next Saturday.
It was all outdoors in parks, usually a several hundred meters from our cars. None of our usual suspect gaffers were available/handy. We had basically 0 time to light things and the director wanted a bunch of wides and tracking shots (both tend to take longer to light). Controlling the light in any meaningful way was not a realistic option. These are exactly the situations when an extra stop of dynamic range is nice to have to keep the sky at least a bit blue, but yet also still have some detail in some of the harsh shadows.
Real tough situation for the filmmaker - they definitely want to keep quality high and have they great ideas, but there are also budgetary and delivery date realities - the difference between a real indie film set and a reddit comments section. 😉
(Also, RIP colorist - there are like 5-6 different color profiles in play across all of the cameras that were used between the original DP and both of us last weekend, hopefully they only have to match 2 or 3 within any given scene)
I'm not sure what ASA 50 has to do with needing extra light on a sunny day. Assuming ~24 fps, that'd give a proper exposure at approximately F/16 in bright sunlight (1/48 second for 180 shutter + sunny 16 rule indicating a 1/50 shutter speed = close enough) and you'd still need to use ND to open up the aperture beyond that. I suspect those lights are for filling in the faces/front of talent in a wide, given that the sun is actually at about a 60-90 degree angle from the lights (judging by shadows). From where the cameras are pointed, the subjects will be backlit.