Yes, there is a difference between the price of android app and ios app. Generally app development cost is a complex issue and requires very a detailed approach. To know more I recommend to read an article in the link above. There is a comprehensive material about this subject![]()
Yeah, especially when there are security concerns related to how you manage user authentication and data. If you don't want to rely on 3rd party providers, rolling your own auth system is challenging for developers and gives them more responsibility and that require costs (related to salary).