Commentary for Kiddushin 120:19

The mishnah and baraita needed to teach the same clause about land and money because if it had taught only the clause about money I would have thought that only in that case would we be uncertain if she is betrothed or not. If he does not show her 200 zuz, she is doubtfully betrothed. But in the case of land, if he has it, we would know and therefore if he does not show it to her, she is not even doubtfully betrothed. Therefore it teaches that even in the case of land, she is still doubtfully betrothed if he does not show her the land.