system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do high-end digital cameras need a physical shutter, while cell phone cameras don't?
gpt
What Ansuz says is really only half the story. Cameras like the Sony A7 don't have a reflex mirror, and are fully electronic, but they still have a physical shutter.

While cameras can operate without a shutter, each pixel must be powered up and down to take a photo. It's simply not possible to achieve this in 1/8000 of a second (a speed that many digital SLRs and mirrorless cameras go down to these days), so the pixels are powered up in the dark, exposed for this short amount of time physically, then powered back down in the dark again. It also allows for more precise timing of the exposure time.

As Ansuz07 says, many shoot video, and they use the shutterless method to do that. As a side note, the 'wobble' that you see when you move digital cameras rapidly is called the 'rolling shutter' effect -- even top end digital cameras would not be able to deal with the amount of data taking a full picture for each frame at the same time would produce, so instead they 'roll' down the frame line by line, only having to process one line of pixels at a time. However, because of this, movement during the 'roll time' will stretch and bend things.