The better cameras have AI built in, so one may or may not need BI AI depending on their needs.
But the biggest issue with the cheaper cameras are they are on sensors designed for 720P or 1080P cameras, so when you throw 4MP or 8MP on them, at night the image suffers because it would need 4 to 8 times more light than a 2MP that is on the same size sensor.
So to make the image brighter, people either crank up the brightness or slow down the shutter, which then makes it difficult to identify moving objects.
The better cameras on ideal MP/sensor ratio can probably go into color whereas the smaller sensor cams probably do not get enough light to go into color.
BI AI has much better results with color images. It can struggle with B/W infrared.
Sensor size is a big deal.
Now you won't know what you don't know and won't know what you are missing until you have experienced a the cheaper cam that is a higher resolution camera on a sensor designed for a lower resolution.
Most people here buy surveillance cameras to capture clean images of perps at night and they are not going to stop and pose for a picture...If it can capture in the night, then it will capture in the day....
Any camera can have settings set to provide a nice bright static image at night by slowing the shutter down and cranking up the gain, but then motion is useless.
Almost any camera can do well in the daytime with enough light, even cameras that are 8MP put on a sensor designed for 2MP. But keep in mind that usually the processor and other stuff are still designed around 2MP, so the camera struggles trying to keep up with 8MP worth of data.
In most instances, you want to get a camera that will perform at your location for the
worse situation - which for most of us is at night when it is dark and there is little to no light.
If a camera performs at night, it is easier to tweak settings to make it work during the day than it is the other way around. The cameras will certainly perform better in the day.
Once you get a camera on the proper MP/sensor ratio, you will see how underperforming a 4MP on a 1/3" sensor is...
Here is another real world example with a deer closer to this sample above. Even with a floodlight, there simply wasn't enough light to make the cheaper 4MP on the 1/2.7" sensor (which is larger than the 1/3" sensor that many cheap cams are on) go into color:
View attachment 150686
And a 4MP on the 1/1.8" sensor camera (different deer LOL) that the camera was able to go to color based on the larger sensor:
View attachment 150687
Which do you think is the better image?
Plus another big key that we stress often is one camera cannot be the be all/see all.
The OP deer is well beyond the distance one should be using for that camera and that can directly impact the ability of BI AI to work.
My images are within 6 feet of the camera.
So the B/W could be good enough for some people and their use case. But the key is regardless of whether you get a cheap or better camera is to not try to do too much with one camera.