Why is it difficult to acquire bitcoin? All of the buying guides or suggestions here on bitcoin.stackexchange seem dated and old. 

Does anyone have any new methods for buying Bitcoin with a disposable or personal debit card?

It's not illegal to have Bitcoin (I don't think) why is it so difficult to acquire Bitcoin?
It really depends from country to country and card companies:

Countries are enforcing regulations on financial institutions: KYC (Know Your Customer) and AML (Anti Money Laundering) - which when applied to disposable cards make them impossible to use in the same way you can't use them to transfer money to anyone's personal account

Second issue is fraud and chargebacks - as explained here: Why is Bitcoin so susceptible to credit card fraud?

Third issue is TAX. Taxman wants to know how much money you have on your bank accounts and that is impossible with bitcoin, unless they can track transaction when you bought it. 

Dutch taxman is asking you to report if you have bitcoins, and in Holland you can buy them using Dutch money transfer system (IDEAL). If you live in England you can buy them from EU bitcoin exchanges/sellers but you need to execute SEPA transfer from your bank which may take few days to clear.