Because in todays legal climate most of the things that were 'gray' back then are forbidden explicitly now. Things that as a kid in my days you'd be receiving a stern talking to for will now cause you to go to jail for very long periods in addition to likely resulting in you filing for bankruptcy.
Also, remember that back then it was way harder to get caught. We did stuff like wardial entire area codes with impunity. The general lack of awareness/focus on computer security combined with non-digital phone switches (oh crossbar, how I loved thee) made it much less risky.
Just one little anecdote for old times' sake. I used a sequential dialer to scan for interesting numbers in the country capital. After hitting one particular number the phone to which the modem was connected rang. This was before the days of anr indicating that whoever backtracked that number in less than a minute had quite a bit of pull. The guy on the other side asked me what we were doing calling that particular number. The phone actually felt hot in my hand and I realized: Busted. So on the spur of the moment I said I was trying to connect to a bbs and he said 'don't call this number again' and hung up. I was still shaking an hour later.
My attitude (and that of most of my contemporaries) was that hacking government computers (in our own country at least) was a Damn Stupid idea.
A corporation will make an ROI decision about pursuing someone. Is it worth their time and money and hassle to pursue, or should they just change the admin password to something other than "secret123" and forget about it.
The government, on the other hand, has whole branches of people with nothing better to do than follow up on this kind of thing, and they aren't motivated by 'profit.'
