Find the place on Google Maps, copy the plus code.
Rather than entering lat/lon coords... except did you get the sign right, or maybe you flipped lat/lon, or got a significant digit out.
There comes a time when a format has so many confusable variants, it’s best to make a new unambiguous format.
I prefer “three words”. You get three words and they identify a location suitably accurate for navigation. https://what3words.com/
At least the algorithm for plus codes is known and can be reused even if Google decides to drop it in the future.
You appear to be conflating other proprietary systems with this open one.
It's a good start though, I'll try other close plus codes until I get it right. Would still have been better to use coordinates.
Having a field that takes lat and lon has all sorts of ways to enter data either incorrectly, or in an unexpected format - if someone has coordinates from some other source they might be typing it in, rather than copy/pasting.
Also, as others have mentioned - plus codes (or Open Location Codes) are an open standard that can be implemented by anyone under an Apache 2.0 license with a whole bunch of example implementations on github[1]
Probably because a plus code is harder for someone to use with non-Google services and open source map tools