I just bought a a video light amaran 200x that can dim 0 to 100%. However, when going from 0% to 1%, there is a big jump in brightness, so is 1% to 2%. I can maybe understand 0% to 1% since it's going from no light to some light (infinite times brighter). But from 1% to 2% it should not have such big jump.

In contrast, when going from 99% to 100% it is hardly noticeable. This may be caused by using D/A converter with low bit depth, same cause as gradient banding on computer monitors

Just out of curiosity, are there lights that can adjust from 1% to 2% with the same imperceptible difference as 99% to 100%? Whether or not this is useful, it is a sign of quality.

Sounds like the difference between a logarithmic versus a linear control.

I don't know the technical reasons. I know in the past reviewers would talk about the ability to dim. I don't know if this was a tech thing they improved on or an economic thing that cheaper lights dimmers didn't dim as well. Some people would complain this light doesn't fully dim to zero or didn't smoothly ramp up.

In usability terms it doesn't often pose a problem. There are scenarios where you might need a subtle effect for the background or hair and you will want a light to dim low especially a powerful light.

It’s been an annoyance with LED lighting since they came out, especially when the equipment also has DMX control. It means 8 bits for brightness, and at the bottom end of the scale it has very big jumps between the bottom 3 or so, with a big jump down to off. It does seem that only a few manufacturers spend the time and money to make the scaling work properly. It’s possible to do it, but only seems to happen on expensive, well designed kit. All mine are steppy at the bottom sadly.

All my Litepanels lights (Astra, Asta 6X, Astra 4X, Astra Soft, Sola, Sola+, SolaENG, Brick, Croma, Luma,) have excellent dimming throughout the entire range. Even when dimmed down to very low levels they are still easy to control in small increments. A critical feature of any light.

Linear, log, or arbitrary control scale.
In terms of f-stop steps with 100% being the brightest (In percent light output)
100, 50, 25, 12,5, 6.75, and so on

If it is a linear control it is a 1 stop step from 1% to 2%

And keep in mind that LED behavior is very different form tungsten lamps.

It boils down to how much engineering the vendor wants to invest in his product.