How does Pandas DataFrame reindex function work with the Copy Parameter when it is set to 'False'?

Question

I could not quite understand the functionality of copy using reindex. When I tested, copy=False is working only if I am giving exactly same index/columns, in sequence. But this not work if I am changing the sequence of columns/indexes

Statement in Pandas documentation says:

"A new object is produced unless the new index is equivalent to the current one and copy=False.

Actual Code ::

dataframe_obj1 = pd.DataFrame(np.arange(16).reshape(4,4), index = [0,1,2,3], columns = [0,1,2,3])
dataframe_obj1_reindex_copy_False = dat.reindex([3,2,1,0], copy=False)
dataframe_obj1.iloc[0,0] = 500
print("""original dataframe - "dataframe_obj1" after reindexing applied is as below""")
print(dataframe_obj1)
print('\n')
print("""re-indexed dataframe - "dataframe_obj1_reindex_copy_False" is  as below""")
print(dataframe_obj1_reindex_copy_False)

Result:

original dataframe - "dataframe_obj1" after reindexing applied is as below
     0   1   2   3
0  500   1   2   3
1    4   5   6   7
2    8   9  10  11
3   12  13  14  15


re-indexed dataframe - "dataframe_obj1_reindex_copy_False" is  as below
    0   1   2   3
3  12  13  14  15
2   8   9  10  11
1   4   5   6   7
0   5   1   2   3

Expecting:

So was expecting value of 500 to get reflected in original data frame as well. But its not happening.

Can someone guide me on this ?

And I guess in case we want to maintain the sequence same and copy=False, how could that be a significant use case as we can achieve it through simple assignment to another variable