The reason Penalty fares were introduced (by BR▸ !!!) is for routes where stations are close together and thus on-train ticket checks are not possible, to allow people to purchase tickets on the train is asking for trouble as there is no incentive for people to pay for their journey and thus "try it on" and the railway looses money, fares go up even more and no money to invest!
Every penalty fare station has clear notices indicating what happens if you board without a ticket and if you choose to ignor them then there's only one person to blame if you get Penalty fared! It may seem harsh if people are running late etc but you can't have one rule for one and a different rule for another. Would you go into Tesco and run out with your shopping without paying for it because you didn't want to queue up because you were late??
Yes you can.
Someone who walks straight to th excess fare window and declares they came from a penalty station but had a reason for no ticket is NOT TRYING TO EVADE PAYING
Someone who tries getting through thr barrier first - IS
Someone who invents their embarkation at an unmanned station - IS
When I declared I got on at egham - there were 4 unmanned stations between there and putney I could have boarded at - but I was honest - and penalised for it
I do take your point BUT the proffessional opportunist fare dodger would arrive at the station and if the barriers were open (which they quite often seem to be at Plymouth and Exeter!!) they would walk staright out of the station, if the barriers were in operation then they would walk staright up to the window and make out that they were late or their dog ate their ticket etc, etc...... I'm not saying that you are a fare dodger but rules are rules!