[jacquesm]

Because people have lives. You can't just pack up and leave normally speaking. Also, being from Romania or Bulgaria is not exactly treated as a preferential attribute when trying to locate work in other European countries. It shouldn't matter but it does.

So even if there are no legal restrictions there are plenty of barriers.

[jheriko]

aside from that most people can't afford to go that far for work... by a long way. it takes money to make money.

[rahimnathwani]

I don't think it's primarily the distance. It costs less than $200 to travel from Sofia to London by bus. This is less than half the median monthly income.

However, getting a job in London or another city will take time, and the cost of essential services like accommodation and public transport will quickly add up.