The knee-jerk, canned response from most parties erring on the side of Law & Order claims:
Even if the door is wide left open, crossing the threshold
is still trespassing, if you don't belong on the property.
This is why burglars are typically charged with breaking AND entering.
Unlawful entry is still a crime one can commit, without breaking open, or otherwise circumventing pro-active security measures.
When it comes to the idea of "hacking" we often find our words fail to describe activities with precision.
The nuanced distinction some tend to draw between "hacking" and "cracking" is mostly relegated to specialized jargon, community slang, and pedantry. Laymen often do not distinguish between the two.
I can't find any reference to "unlawful entry" in the law books. There is a Kurt Russell film by that name though.
Trespassing is an actual crime, but it does not fit your description, at least in California. Here, you must have an intent to interfere with the owner's property for it to be considered trespassing. If I enter your open door because I want to invite you to a party, or use your restroom, or hang out with your cats and play video games until you come home I have not committed any crime. Well maybe you could get me for stealing water and electricity, but the entry is not a crime.
"Breaking and entering" is also not a crime in California. However, if you actually steal something that is burglary, which is a crime, and does not require forced entry.
Unlawful entry is still a crime one can commit, without breaking open, or otherwise circumventing pro-active security measures.
When it comes to the idea of "hacking" we often find our words fail to describe activities with precision.
The nuanced distinction some tend to draw between "hacking" and "cracking" is mostly relegated to specialized jargon, community slang, and pedantry. Laymen often do not distinguish between the two.