From a legal standpoint, there is way more to cover with those services. All sorts of hoops (NDA, compliance, etc.) would have to be jumped through. At my current employer, those services not being on our property under our complete control makes our lawyers nervous; counterfeits of our product are an existential threat to us, and keeping tight control over the software and electrical implementation details is paramount. Any idea involving a third-party service hosting sensitive engineering data goes straight into the shitcan.

If you managed to address the legal and security concerns, you'd have to fight against decades of momentum and user entrenchment. Drive and Dropbox are rare; any customers or vendors that you're working with will probably have the headache of figuring out how to interface with these services instead of just applying their ~25 years of experience administering massively powerful Windows services. Power users have assimilated those 25 years of workflow into their very being, and all the added complexity of SMB/Windows shares and other related services are extremely powerful tools that help them ensure that the right people have access to what they need and no access to what they don't. In-house tools are written to integrate with the existing infrastructure, and nobody has enough knowledge or balls to attempt replacing them. Internal data sharing services are generally based on software which has been continuously improving for decades, and has best-in-class feature sets and support.

The points above are themes that I've encountered pretty much universally in every engineering firm that I've worked for or interfaced with.