Its not easy as it sounds. Its not a transfer per say, its a new petition. Recently premium processing was stopped. Many H1B transfers were in limbo. If an employee transfers when he has I-140, his greencard process might get jeopardized. There are many quirks for an employee to change his employers. Many employers will not allow an employee to join unless his petition is approved. This is also good for the employee, because there are high chances that an H1B transfer can go wrong. So no, its not easy.