There are many reasons why users find it harder to use a website on a mobile phone then on a desktop:
Recently the University Of Albert did a survey where they asked people to read a text on a desktop monitor or on a mobile phone.
The comprehension in reading of the desktop users was 39%. What do you think the mobile users scored?
The mobile users only scored 18,39%!
The reading level on a normal desktop was already quite low, on a mobile device it was more than half lower!
The only difference between the user groups where the screen sizes.Why then is there such a big difference in understanding the text? The study found a couple of reasons:
Writing for the web is already quite different then writing for print. But writing for mobile is definitely something we have to think about when building websites.