The UK standard stock fits in auto-barrier slots, that is the main reason why ELGAR (which uses the larger ticketing stock) is now limited to Eurostar. Barriers don't really exist on mainline rail stations in mainland Europe, excluding Eurostar, so the compatibility of the tickets with auto-barriers is not an issue. Eurostar has special custom barriers, which now use barcodes on ELGAR tickets at "check-in barriers".
Tickets for local and longer-distance journeys in mainland Europe don't tend to be issued on large ticketing stock nowadays - unless you pay a fee when you order the tickets online/via telesales. DB in Germany, NS in the Netherlands and SNCB in Belgium generally issue, with exceptions, small UK-style tickets from their machines and offices (although they are more like paper) to their customers.
Don't underestimate the rise in print at home ticketing - it's extremely common now in some countries, including Germany and Spain. It's now offered as the fee-free option on Eurostar and Deutsche Bahn (who offer it for all tickets - including rovers and rangers). It has practically wiped out the traditional ticketing on long distance journeys in Germany.