Most countries do not have prescreening or data sharing treaties. Even in the case where two countries do have it, not all entrance criteria can be determined b

Most countries do not have prescreening or data sharing treaties. Even in the case where two countries do have it, not all entrance criteria can be determined by electronic records. Countries reserve the right to check the traveller themselves before they permit entry. Here's a list of common reasons for the UK to refuse entry on arrival: https://www.gov.uk/government/publications/suitability-refusal-of-entry-on-arrival-in-the-united-kingdom-immigration-staff-guidance https://www.gov.uk/government/publications/suitability-refus... Some examples: * Your valid travel document (as communicated digitally) turns out to be invalid when you actually present it * You got a tourist visa, not a work visa, so why do you have work tools in your luggage? * You turn up infected with Ebola