> Why on earth is Apple, a good tech company, with a culture of secrecy, using slack? Can it not build its own secure version of slack?

What else are they going to do with all that cash they're sitting on?

Also in this way they are being patriotic and supporting 'American innovation'; i.e. the American Intellectual Property regime [1].

[1] https://tribunemag.co.uk/2019/01/abolish-silicon-valley