If you're asking if tech built outside the US carries with it an increased risk of sending personal data without your explicit permission, the answer is somewhat complicated. I'll take a stab at answering that.
In general, the answer is, it (potentially) depends on the operating system and installed software. There's also software commands in the bios that a committed party could possibly build into the firmware that could act in this manner.
Apps are clearly the most common method of data mining. The question then is, how well are the apps controlled by the company overseeing device security.
Android devices while being more customizable, are at a far, FAR greater risk of security breaches due to the innumerable software versions and resulting fractured ecosystems involved. The more versions and less centrally controlled, the higher the risk that something will 'get through.'
Apple's death grip on almost the entire ecosystem combined with an impeccable company philosophy dedicated to security and privacy, result in a more fleshed-out secure platform. That being said, there are issues with both platforms' apps farming data without the knowledge /permission of the user. It's just that the nature of a fractured/non-centralized platform, is inevitably less secure.
Malicious code written for the express purpose of stealing data can be very difficult to determine. To the best of my observations (and that of the general tech industry as a whole), Apple has a significantly better handle on this for reasons I mentioned.
Additionally, there's 'social engineering' (fooling people into installing bad software), drive by installations that don't require any action on the part of the user, which installs itself simply by visiting certain websites (no click necessary), trojan files with malicious code preinstalled, etc, etc. Most of these can certainly be platform agnostic, this is still an area where Apple has a better handle on things. While at one point in the past, the old axiom of "security through obscurity" MAY have held a morsel of truth, the fact is that today, Apple's indisputable title as king of hill, has largely laid that argument to rest, since sheer numbers reveal iOS to be far less vulnerable (though certainly not immune) to these security issues.
Many apps and all operating systems map, access or collect data that users may consider "private." However, the function of many apps rely on the ability to access such data in order to carry out the tasks unique to their specific function. Most credible software authors build in anonymous data collection to improve future software versions and to establish whether or not their software functions as intended. So, while data may indeed be being transferred, it does so in a manner either not in a way in which can be used inappropriately, or is kept from non-critical usage by the author. However, there are increasingly sophisticated and unscrupulous developers who build code into their apps and applets in order to mine personal data for criminal and commercial gain. There are committed actors who, through both political and ideological greed and espionage can and DO threaten our precious privacy, and they often use the porous nature of international borders, but in my mind, it's more a matter of the fact that it's easier to get away with it outside of the US, due to fewer (or perhaps 'looser') inherent roadblocks, than due to any particularly advanced security practices used within the US.
I hope that I've addressed some of your concerns without sounding too much like an Apple "cultie,"
but the facts are what they are.