pytest-selenium can pass only strings as command line capabilities.
Since IE requires a bool there, having this on command line does not work.

There are some tricks in this codebase that can be tried

(They say porn mode is faster than clean session)

    # https://github.com/jirikuchta/selenium-webtests/blob/15b9225a8ddd352c5029cc463a1d02fb06520148/seleniumwebtests/testcase.py
    # start IE in private mode to prevent storing cookies
    capabilities["ie.forceCreateProcessApi"] = 1
    capabilities["ie.browserCommandLineSwitches"] = "-private"

    # hack to force clean session on IE; pytest-selenium would set it to 'true', not True
    # for capability in capabilities):
    if capability[0] == 'ie.ensureCleanSession':
        capabilities["ie.ensureCleanSession"] = True
        break

… --local-chrome

* Increase number of retries (for expanding the tree)
* Do some retries for waiting for angular
    (angular may not be yet loaded, got
    E       selenium.common.exceptions.WebDriverException: Message: ReferenceError: angular is not defined
    )

* Double one more bloody timeout