Many reasons really. Some others have alluded in other comments: * Fixing bugs isn't sexy. Constantly pushing new features is. Tech debt therefore isn't manage

Many reasons really. Some others have alluded in other comments: * Fixing bugs isn't sexy. Constantly pushing new features is. Tech debt therefore isn't managed properly. I am leaving a job right now because of this. * Problems with performance arise because developers frequently only test the application on their machine and/or phone and developer typically will have nice hardware that will run the application quickly. * Mobile applications only get tested in areas where there is a good signal and issues that occur when signal strength and/or bandwidth are poor aren't accounted for. * Decisions on what get prioritised are based entirely on user metrics collected in app. Which means anyone that blocks this reporting or doesn't fit neatly into the most common scenarios will be left out in the cold or issues de-prioritised and possibly never fixed. * Tech debt at these companies is insane. Your app probably has a large client and server side solution that probably takes months for someone to be proficient even in making the most basic changes. There will be 500 lines in each switch statement blocks, classes that are 1000s of lines long etc. etc. This is due to tech debt not being managed and people just hacking to get stuff done to sprint deadlines. * There will be 1000s of long standing bugs that can only be reproduced on particular devices (which may or may not affect you). Frequently devs might not even be able to get their hands on the device to actually fix said issue. * I would wage in some cases the info-sec team will have ridiculous hang-ups about plugging in a phone via USB to a PC / Mac to debug. Frequently issues will be debugged via archaic or jerry rigged solutions which seem ridiculous to most freelance / non-corp devs.