If Lee was really, really
smart,sincere and serious, she should have made a formal declaration to renounce her
U.S. citizenship.     She should have appeared in person at a U.S.
Consulate in another country, signed an oath of renunciation and
handed over her US passport.    If she renounced her US citizenship
formally and got accepted by the State Department of the United
States, then her name would have been published in the Federal Register as a
legal notice to anyone who might be trying to locate her –
including IRS.   This would be a rock solid evidence that she is no
longer an U.S. citizen.

Did she understand the
steps required to give up her U.S. nationality?   I would think so.   
When she applied for U.S. citizenship, she knew it did take a lot of
steps to “make her dream come true”.   Similarly, if she wants to
give it up, there will be a lot of steps needed for her to follow too.

Why didn't she do that?   
Because of her greed and stupidity.    When she got elected as Taipei
City Councilwoman long, long time ago, she was still sitting on the
fence.   She was still uncommitted to staying in Taiwan for the rest
of her life.  Besides, she didn't expect that she could become
what she is today( a shining lawmaker).   The lesson we got from her
misfortune is that in this world, everything has a price.   If you
made a mistake, you have to pay the price.   For example, if you put
your hard-earned money in the wrong people's hands, you might end up losing all
you have.   That's the price you have to pay.     The price Lee paid
for the mistake she made obviously is very, very hefty.