Shouldn't really single out this one, but haven't seen a petition for a while, and they annoy me...
The problem with petitions is they live in an isolated little world where there is only one problem with an easy solution - fuel tax is too high, and it could be lowered, which would solve the problem. Marvellous, let's do it and move on to the next big problem - while we're at it we can abolish income tax, because that's unpopular, and abolish VAT because i'm sure no one would object to that either.
What a credible petition needs is a viable alternative. What do they propose we do to replace the lost tax? They haven't suggested anything, so what if i proposed we cut road building so that the hauliers sit in traffic jams all day, or put up road tax on lorries by 100x to make up the difference?
How about something that (apparently) doesn't impact hauliers - let's put VAT up a little more. Oh, but then people would buy less, we'd need less goods in shops, need to manufacture less, and so need less deliveries. They've just petitioned themselves out of jobs! Or put up income tax - but no, then people would have less money to spend, people would buy less, we'd need less goods in shops, need to manufacture less, and so need less deliveries. They've just petitioned themselves out of jobs again!
The point i'm trying to make is that the economy is a hugely complex set of interactions between billions of transactions, thousands of laws and taxes, and a lot of public spending, and if you change one the rest will adjust to compensate. Petitions against single issues are ultimately pointless, because of the reasons i gave above. Everyone would sign a petition to reduce one tax in isolation. But unless you tell the government that "we want to reduce this tax, but don't mind you putting up this other tax which will raise the same revenue" then the simple answer is that, actually, yes fuel tax is unpopular, but putting up income tax would be even more unpopular, so it's simply the lesser of two evils.
David