Building a camera that supports AR filters, along with common controls like using the back or front facing camera, enabling flash and supporting drag up/down to zoom, while maintaining 60fps isn't easy.
The fact you can do this with javascript (and swift for AR) is pretty magical.
We do have some limitations, like enabling flash on the front camera, that requires some clever logic that uses the screen as a ring light.
That will be shipping in the next release!