Oracle Hot Backup Theory

After a hot backup, where all tablespaces are placed in backup mode seperately; i.e.

alter tablespace user_data start backup;

each datafile will have a different Checkpoint SCN in its header; with the equivalent redo log files which will bring it up to date.

Why doesn't this non-sync of Checkpoint SCN cause a problem when restoring and recovering these datafiles? The "checkpoint" SCN of each datafile is different from other datafiles and probably different from the control file's recorded SCN as well; doesn't this cause a problem?

Addition

Doesn't the inconsistency of the SCN in the datafiles cause a problem when SMON checks them once we decide to restore and recover the database using the hot backup?